Uh no, that’s not how this works. The lifetime subscription only makes financial sense if you plan to spend more than 3 years on WaniKani - or more than 2 years if you happen to start exactly when the yearly sale is happening. That’s not an insanely slow pace, but it’s also not exactly fast. Plus you have to take into account people who get lifetime after they already paid for maybe a year or so.
In other words, if WK was faster, they would have to lower the price of lifetime or fewer people would buy it - generating less profit for them.
Businesses don’t offer discounts, lifetime subscriptions, etc. out of a goodness of their hearts but because it creates good-will with potential customers and convinces them to buy things they may not ultimately need. The drop-off rate for WK is pretty high and if you manage to convert at least some of these users that will later drop off to lifetime customers, it’s very lucrative.
I don’t fault WK at all for doing stuff like that, it’s just common sense pricing models, but let’s not pretend that there isn’t a business rationale for this.
As for the topic itself, I agree that the pacing of WK is weird and inflexible, although I wouldn’t say it’s too “slow”(*) once you’ve reached later levels. But without reorder script etc. it’s just not very balanced. Learning all the Kanji for a level at once and then learning all the vocab doesn’t strike me as a very good idea. That’s why I’m now using reorder to learn 5-10 Kanji + 10 vocab items a day, but it’s honestly a bit of a pain.
That said, these complaints have been around forever and nothing to me seems to indicate that WK is ever going to make the system more flexible, so I don’t see any alternative besides either accepting it and continuing with WK as intended, or dropping out and go use something else instead.
(*) What makes WK “slow” for me is not the gatekeeping between levels but the amount of vocab, a lot of which seems redundant in terms of teaching you certain readings. There’s absolutely no way to really skip vocab, you could maybe do some stuff with reordering, but I suppose that’s gonna be rather painful.