Ooo! Controversy!
Hmmm, I guess I still haven't made my point too clearly...
Ok... take Zelda (not exactly a platform game, but I still have the same point.)
I've played and beaten both of the N64 games and most (I can't say all, I've never owned a NES) of the others.
The new games: graphically appealing, nice challenge, good story, lots of details... yet not the same. The Z-targeting battle system gave for some nice duels, but it can't compare to running aimlessly through the overworld and being smothered by fierce (well, not exactly fierce, but numerous! And they still hurt!) enimies, fending them off with an arsenal off items that had applicable uses (the ice wand: unneccesary, but great fun!) other than to topple one obstacle to get to the next level, the constant beeping reminding you that one more wrong step will mean the end of the line and another embarassing notch on the death toll.
I'm not exactly sure how to express what I'm saying very clearly, but I just played A Link to the Past last weekend. Great fun, great challenge. (Maybe the simplicity of the gameplay leads to more complexity of the game? I dunno.)
I'm also not saying anything against 3D games, but if there is a way to parllel that feel that you get with the supreme organized chaos and panic of trying frantically to right yourself onto a platform while accidentally knocking yourself off of it for the third time while trying to evade a barrage of enemy fire in a platformer, or the sheer joy of finding a well-hiden secret, or getting and brand new item that lets you knock soldiers off cliffs in a new and exciting manner (Zelda, of course,) then the game industry has yet to achieve it.
(Sorry for the lack of Mario citings, but Zelda was fresh on my mind)