Fun, and a programmatic perspective. However, it can be too easy and fun to get super caught up in these details, if your goals are some level of fluency and ability to communicate/read. The majority of people that I know who have gained any level of fluency in Japanese as an adult mostly avoided stuff like this because (for many people; of course everybody is different) doing all of this mental math to dive down to the last detail was nowhere near as effective as some speaking and reading drills.
By all means, it is fun to play with a language. And every person's brain works differently.
I like to use this metaphor, though. You're hiking a mountain, this journey to the "peak" is reaching some goal of fluency.
It's fun to stop and look at rocks, examining, comparing and whatnot. But it doesn't necessarily get you closer to the peak. I mean, it might, because you'll better understand your footing every-so-slightly. Not a perfect metaphor.
I'm a bit dismayed by all the negativity you're getting. Thanks for all your level-headed and detailed responses here.
I have a hard time understanding why people object to this kind of attempt to systematize something that conventionally relies on rote learning. I've always found that figuring out the underlying rules helps with the rote learning. When you see some new word or conjugation, it's super helpful to have a method for explaining why it's that way; it helps fix it in your mind.
I wonder if native speakers object to this approach because it isn't really how you learn as a kid. You don't learn any abstract rules, you just absorb a huge amount of training material and construct your own model. But that doesn't mean adults need to learn in the same way; we can and should leverage our painfully-acquired knowledge and skills from other domains.
Maybe it’s not very clear but I don’t suggest studying from articles like this alone. Obviously you need to do sentence drills and talk to a tutor or native speakers to have any chance of success. I still find documenting my mental model helpful because most articles I’ve seen before were not teaching it clearly enough for my taste.
It is definitely well written and presented.