(The following post has no angst-y/sarcasm-ish tone to it, so take it lightly.)
That doesn't necessarily reflect my stance on whether it was innovative or not. I do believe the 4 player addition to be a great innovation.
I have played two player with my ex-girlfriend. This is where NSMB Wii stores its most awesome fun and it is only when you're playing with people that the game is truly worth the almost $60 price tag.
With the Wii's wi-fi service being disgusting at best, I'm aware that, realistically, NSMB Wii would probably have had similar issues that Mario Kart had lag-wise... as in: not so much button lag (e.g. Brawl) as it is... the servers just can't keep up (but try and keep everything smooth and flowing) which results in the "game world" (for lack of a better term) not being able to tell where the hell all the racers/items/etc. are supposed to be in order to stay in sync across all players' screens. In NSMB Wii, I imagine I'd want to jump on the other player's head, then I'd suddenly see them appear somewhere away from me and I'd end up dying, for example. However, you'd think that since all the action would be confined to one screen and not much would be going (not as much to render as Brawl, I'd assume), that it could be marginally better, if that's how it works (correct me if I'm wrong) in the first place... although.. Brawl was single screen and it was terrible, but tons of stuff was happening on the screen at once constantly, however.
The reason I complain about no online co-op is because I knew that I'd definitely have tons more fun with other people, but I knew that the only way that would've been possible would've been to find like-minded Mario gamers, such as most of the people registered on my Wii and play with them over wi-fi.
I pushed for it a lot because I wanted to be able to enjoy the game for a very long time; Multiplayer is tons of fun, but I wanted to be able to experience that way more often rather than only when I ended up going to my ex-girlfriend's house to hang out and maybe play 40 minutes worth of NSMB Wii only one time... come home later... then play single player for days on end.
I can get a few buddies and we can go pick up and play Forza 3, GTA IV, or Modern Warfare 2 and have tons of fun over LIVE, so what's wrong with asking why I can't grab a few Mario buddies and play some NSMB and with saying that wi-fi should be expected next time around?