Well I've been a hardcore Nintendo fan since NES, I've never owned an PS or Xbox, because I think Nintendo has the best games period.
But a lot of companies have dismissed Nintendo, back when they first stuck with cartridges over compact disc. So when the Wii was set to arrive last year, those same companies never had Wii games in production because they didn't think the Wii was going to kick butt... and now we all know it does kick butt , and Nintendo is back on top.Â
So to answer your question.. Companies weren't prepared with the success of the Nintendo Wii and now they are scrambling to produce games for it, and most stopped making PS3 titles and concentrate on making Wii titles. So in the next year or so, the "scene" will be poppin'.
http://www.vgchartz.com/