In order to learn how to read and speak, one has to know vocabulary.
If the vocabulary doesn’t have the same reading than the kanjis composing it, what is the point of actually learning them?
Isn’t it easier and faster to just learn the vocabulary?
I mean, why would i learn mathematics to understand english reading ? (couldn’t come with another comparaison sorry lol)
Well, each kanji doesn’t show up in a single word…
Sure you can learn the word 水(みず) and read it just fine, but then you’ll have no clue how to read the same kanji in the word 水銀（すいぎん).
The reading you learn on Wanikani is the most common one. So, while it’s not true for all words, you will be able to read many vocab’s readings before having learned them, which is far easier than learning them all on their own.
Kanji can have multiple readings (on’yomi and kun’yomi), and it’s important to know them all (or at least the most common ones). Learning the reading for the kanji is important when learning vocab utilizing that kanji
Ex: 外 (meaning: outside)
外 learned as a kanji (on’yomi reading) → がい
外 as vocab (kun’yomi reading) → そと
Vocab words utilizing 外:
外国人 (foreigner) → がいこくじん
外国 (foreign country) → がいこく
外交 (diplomat) → がいこう
Learning 外 just as a vocab reading (そと) would make learning other vocabulary words more difficult. This is just one example, as you keep learning the readings and begin to familiarize yourself with the language you’ll soon understand the importance of learning the kanji readings 
Wrong comparison. What you should be asking yourself is “Why should I learn the alphabet in order to be able to read Japanese?”
Now, the English alphabet has 26 letters. Japanese? Thousands Plus, Kanji have several different readings, so take that into consideration too.
As for usefulness…take, for example the kanji 無. This kanji is verrry common and has a reading of む in most cases. If you know this, as well as the fact that it means nothing ( or something along those lines), it makes reading every word that composes it MUCH easier. Learning kanji is doing yourself a favor,
Furthermore it allows you to guess the meanings and readings of unknown words with pretty decent accuracy. One time when I went to karaoke with a couple buddies, one of the tabs was 新曲. I never learned that word, but I learned 新 means new and is read しん and 曲 means tune or music ( or bend in some cases but thats not important rn) and is read as きょく. From this I was able to understand and read a word I otherwise wouldnt have known.
I wouldnt exactly compare it to learning the alphabet, as its more important than that imo. Kanji doesnt just tell you how to read something, but they also carry meaning. Often this meaning will allow you to better remember, or guess at the definition of some vocab word.
To answer your question: I understand why you would think so, but it is not faster nor easier. In order to become truly fluent you will need to learn tens of thousands of words. learning a couple thousand kanji will make that task soooooo much easier in the long run.
The pink-background “kanji” readings you learn in WaniKani are what you’ll most commonly encounter whenever it appears as a compound word (with other kanji adjacent to it). A lone kanji character by itself will almost always read differently than it does when combined with other kanji.
As @Vanilla said, I’ve been able to correctly read plenty of words I’ve never seen before because WK taught me to expect common readings.
I feel the need to stress this further.
Kanji are the alphabet of Japanese alongside Katakana and Hiragana. Not learning the Kanji but learning the Vocab is essentially trying to learn English word by word without learning their letters.
I would never be able to see myself learning kanji vocabulary without having any understanding of kanji in the first place… that would be a daunting task to say the least. It’s just gonna be a bit of a huzzle to learn all the readings that WK is not listing when it comes to specific kanjis, learning every reading of every single kanji by just studying kanji-vocab? Man, that doesn’t sound fun.
Just recently I learned that 外 can be read ほか in certain circumstances.
It would be crazy to try to learn the vocabulary directly. Even if you give each kanji a weight according to its
number of readings, it is quite evident that the total will be far below the vocabulary you have to learn (I am not talking about the WK 6000 so words. Quite obviously, much more is needed)
Secondly, kanji have a meaning, which can greatly help you to find the meaning of the word. You will soon discover that you understand words that you are not (yet) able to pronounce. That happens to all students of Japanese.
What? That’s interesting, does this happen when 外 is used with a similar meaning to “other” (他)?
I’d be curious to know what inspired this, because I can’t really think of any kanji on WK that would apply to your complaint, of having no associated vocab that use their reading. There are some in the level 50+ kanji that are associated with names and WK hasn’t added the name vocab items yet, but obviously you’re not talking about those.
大人 gets taught in L1. Perhaps that’s the one he’s caught on, as it is … ateji? Not sure what the word for unique readings is.
You’re thinking of jukujikun, where kanji is used to convey the meaning (but not the reading) of an existing Japanese word, for example 従兄弟 and 一昨日.
That’s the one!
Ah, 大人. The word that is pronounced like printer ink and NOT like a tasty Moroccan stew.
I agree with the others; your mathematics to English analogy is quite off the mark. However, I wouldn’t go as far as to say that disregarding kanji readings is the same as not learning letters themselves.
Tell me, have you ever ridden a twocycle? Which do you like more, squares, circles, or threeangles? In a book, do you normally root for the maintagonist or the againstagonist?
Sure, the above questions may seem facetious, but in a language where you can spell out words to figure out how they’re said, these questions become much more serious. The way to type Japanese on a computer is to type out the reading, creating the hiragana, then locating the proper kanji that go with them. If you use only the kunyomi readings (as most early vocabulary on WK will teach you), you will likely never find any word you actually want once you start learning more jukugo (compound words).
Sure, in English, you can learn what “main character” and “opposing character” mean, but learning those will not help you understand when someone says “protagonist” or “antagonist.” English has letters we can use to figure out at least a ballpark of a reading, and we have WAY more vowel and consonant sounds than Japanese, meaning less likeliness of two readings being the same.
Here’s a very relevant, strong example most people would understand. Have you ever heard of the city of Higashimiyako? Probably not, right? That’s because it’s read Tokyo (or Toukyou by kana). If you only learn the vocabulary, than Tokyo (made with the characters for East and Capital) is Higashi, meaning East, and Miyako, meaning Capital. By learning the kanji readings (usually onyomi), you’ll understand how to acquire much more vocabulary without confusing natives.
Like @Leebo said, I can’t think of any kanji I’ve seen yet where the readings are used at all, but it’s true that WaniKani does have some less than practical instances of reading timings. One example would be 刀 learned at level 2. You learn the reading とう but then are given かたな for the vocabulary. You then don’t see the other reading for ten entire levels, around two months time at max speed, and that vocabulary is the ONLY one in the database to use the reading. It’s somewhat unfortunate when these rare instances happen, but it’s done for a reason. The radical is used in a lot of kanji, the vocabulary term is pretty much known universally in the English speaking world, and all of its jukugo use kanji that beginners shouldn’t be seeing.
If your argument is really about being against learning any reading but the one used standalone, I honestly think you may want to reconsider learning Japanese. If it’s related to the latter, then pick up some resources alongside WaniKani, as most of us do. If you want more vocabulary related to the readings, hit up jisho.org and search by the reading you want.
There’s another huge side benefit of learning all of the readings. As you get more kanji and vocabulary under your belt, you’ll get a “feel” of what the right reading is. Learning Japanese names is downright suffering, as there is a large list of readings that are pretty much used exclusively in names. When I encountered a person with the name 外山, I realized immediately that none of the readings I knew for it sounded correct when paired with やま, so rather than guessing, I asked how I read it and learned that と is a possible reading for it. If I’d learned only そと, I would’ve defaulted to そとやま and thoroughly embarrassed myself. Instead, I tried out がいやま、そとやま、and はずやま (I could have tried さん、but that is much less common in names), realized none of them worked well, and assumed their was another reading I didn’t know.
In English, the worst we can do to a word is either use the wrong vowel sound or put the stress on the wrong part of the word. In most cases of a native committing this error, we can immediately realize what they were trying to say. Japanese has a large amount of homophones, however, so it is much less likely they can figure out what you meant to say.
刀 is an unfortunate exception as it can be read as とう all by itself as well.
The phrase where this happens is 思いの外 - unexpected