I also don't think this is especially deep—that I think this approach to teaching verb conjugation is a bad approach and I don’t think there is this much to say about it.

People off the street are obviously not learning Japanese verb conjugations in isolation. If they are learning it at all, they probably have some broader goals involving spoken or written fluency, and these people are gonna fire up DuoLingo or sign up for a class or something. Japanese verb conjugations are simple and easy to learn but they are usually not taught day 1, and you are not expected to learn the whole table at once, but one or two conjugations at a time along with practice using that conjugation.

So if the pitch is, “this system works for teaching English speakers off the street how to conjugate verbs in Japanese” it seems to me like the goal is a little artificial and maybe not representative.

I think the call to “engineering mindset” may be illuminative, because engineers are likely to have unwarranted confidence in fields outside of their expertise. Engineers in practice often think that they can use engineering skills (broadly speaking) to solve education problems, learn foreign languages, or solve social problems. The phenomenon is sometimes called “engineer’s disease” or “engineer’s syndrome”. What I wonder is whether there is something about engineering mindset that is counterproductive outside of engineering fields—this seems plausible, because it explains why we don’t just teach everyone to use an engineering mindset.