From what I was taught when I asked, Japanese people dislike the English-style suits (dark green, brown, etc.). Maybe is it just that black suits match better their hair colour, and also why older men (with greying hair) tend to wear more grey suits. (?)
But it's undeniable, as FirstHousePooka mentioned, that conformity plays a major role too. Japanese people rarely wear "hade" (flashy or original) neckties for instance.