I agree with your suggestion wholeheartedly, especially since WaniKani has a pretty garish UI where colors can mean multiple things (item type and SRS level) and the meaning vs reading prompts do not stand out as visually unique in the way that, say, the kanji vs. vocab (pink vs purple) do. This, to me, is a design problem that sometimes makes me overlook whether I’m being asked the meaning or the reading. My brain responds way more to color prompts than text prompts, so the item type catches my attention while the meaning/reading text gets skimmed over by my brain as secondary information.
When you’re drilling reviews over and over repetitively, accidentally entering a reading rather than a meaning is what I call “an honest mistake”, not an incorrect answer. It’s not really something you can control 100% of the time, and I think just getting the big red “wrong” and unnecessarily delaying that review further is more punishing of your day’s stress level, busyness, alertness, focus, brain type, and a number of other factors, rather than your knowledge of the topic, since you entered a correct answer for that item (assuming you did write the correct reading), just not the one it was asking for.
That said I don’t expect them to change it. I use the ignore script for this reason. Just wanted to say that I agree with you.
Edit after reading Kai_973’s comment… holy crap I never even noticed the difference in black vs white background when asked for a reading vs meaning, and I’m on level 7… Thanks for the heads up. I think it will help me.