That's great!
What you have to understand about Nintendo is that they didn't have chance with 3rd editors this time.
You say why they don't improve that much their series? Why aren't they creating new licenses? The answer is easy: Nintendo's games are the only one that sells so they based their games on sure values: Mario, Zelda, Fitness and Sports, which the 2 last are getting in popularity nowadays.
That's not their fault. They just need to know that they will make money and then create different games.
Mario Galaxy is the only game that is totally different of its predecessor, Sunshine, and also one of the best game of all time. They did a great job.