Rhythm Heaven may be successful in Japan based on Tsunku alone, but it never seems to take off in the other regions. Like, at all.
It's also saying quite a lot when all it gets in Smash is one random-assed Smash Run enemy (and a rare "bonus enemy", at that), a few trophies (a grand total that can only be counted with one hand, going across both versions), and two songs (in a downloadable stage, no less). Why there wasn't at least a goddamn RH stage is beyond me.