I really think they have to be careful, too, of the example. It isn't ok to just make a poor looking group of 3 mini-games and sell them for a lot of money. Third parties will love to do it, too, if Nintendo sets that example.
Nintendo's flaw has always been presentation. Graphics aside, they don't present the games with much flair. If they made the characters look like humanoids, not Fisher Price rejects, it would help a lot. Let's face it, art direction is eons more important than polygon count, but the characters in WiiSports are atrocious in both those categories. If they were smart they'd go for either highly stylized or more realistic. As it is the thing looks like one of those cheap games you buy with a plastic bat and it plugs into your VCR.
I guess I just don't see why Nintendo can't make the games flashy, appealing and still lighthearted and very accessable. All those things make more sense than the current character design. They also need to pack this in and have 4 or more sports.