I honestly think they should just keep doing it there style, and not change it, Mario was oneof the first games ever, and it is still a great original game, just let them keep doing it there style in my opinion.
Yeah, they can definitely do better than just a galaxy! They can do Super Mario: Universe or Super Mario: Stars. Maybe they can do Super Mario: The 9th Dimension, where Bowser is being captured by Peach and then Mario has to save him. Lol. Being less sarcastic, it would be sick if there was a Super Mario: Digital Age where Bowser captures Peach and hides her in the depths of the internet.
Mario Galaxy is a great game, I don't see anything wrong with it. It's different then most other games for the Wii. Mario has it's own unique style and I don't see why it should change, maybe tell us why you think it should?