Nintendo focuses too much on the party games, like Mario Kart and all the sports, and not enough on the main stream games. Princess Daisy, who appeared in one main stream mario game, practically appears in every party game the series puts out. They did the same thing with Rosalina, and with Waluigi, and he hasn't even appeared in the main series yet. Nintendo just pulled his character out of thin air and he's probably a good character and all, but it would be a lot easier to tell if he, oh I don't know, actually appeared in the main series.
Nintendo are pretty obviously running out of ideas. Galaxy was fun, but a sequel was hardly needed. Galaxy 2 was pretty much an extra level pack for Galaxy 1 with one or two new gimmicks. The New Super Mario Bros. series has grown stale and boring and has nothing going for it at all. Come on Nintendo, coins are not gimmicks.