New Super Mario Bros. Wii

[SkyMyl]

Online would have been nice, even though most of the people who play it online would probably suck.

Close, but no. It would have been filled with:

A. People who play the game normally
B. People who want to speedrun through the game online and ragequit if you suck
C. People who naturally suck
D. People who would be dicks and chuck players of edges

[bluaki]

I don't know how games like LBP work with online, but the fact is that no matter how good your servers are, there is still definite lag and latency in online gaming, especially with users who don't have excellent internet connections. In a game like the 2D Marios, where timing is everything including with interactions between characters, even a bit of latency is plenty enough to break the game.

Most of the other game genres that heavily use online don't require such sub-second preciseness. For RTS games, a single click may take a second to go through with very little negative effect on gameplay. Though I'm not too familiar with FPS games, typical latency is low enough to account for the supposed time it takes a character to fire a bullet.