I had a thought:
In the next NSMB game, should they add in levels from old Mario platformers, a la the Retro Grand Prix in Mario Kart? It would work similarly to the Super Mario Advance games; improved graphics, some extra stuff thrown in for the new engine. What do you think? That would certainly get me interested in a new NSMB game.

Everybody keeps complaining about NSMB not doing anything new, adding retro levels would probably only add more to that. :S Personally i think it would be kidna cool. NSMB2 is having DLC based on older levels, maybe NSMBU could do something similair?

NSMB2's retro pack is on the right track, but wasn't quite what I had in mind. The retro courses in Mario Kart are always fun; just as good as finding out what the new courses are is seeing what old tracks they've redone for the new game. Shouldn't the same apply to NSMB?