[laurieg]

I think you're probably falling into a common trap: There are plenty of exceptions, you just don't know them yet.

For sure, Japanese verbs are more regular than English verbs. But most materials written about Japanese are aimed squarely at beginners. They naturally skip over any foibles for pedagogical reasons. There isn't all that much written (in English) about tricky sentences, syntactic ambiguity and similar mistakes.

[klodolph]

There's a theory that humans have a certain "complexity budget" for languages. People will add things to simple languages, and forget things from complex languages, to arrive at some sort of equilibrium. Language complexity is a bit of a touchy subject though.

By comparison, Japanese might have simpler syntax and phonology than English, but higher orthographic and morphological complexity (and English is already orthographically complex).