What people seem to fail to realize is that this is the first generation of real online capabilities for a nintendo console (not handheld, or SEGA or some of the older on-line capable systems). Lets just keep that in mind that the Xbox360 and PS3 are the second generations of online capable systems for Sony and Microsoft.
I can understand that people are annoyed at the lack of multiplayer games and that people say that Nintendo should have thought-ahead and added multiplayer capabilities to it's games. While this is true that it probably would have been a better move to do this right off the bat the problem is getting everything set-up properly.
I understand people's feelings about this but we should try to keep things in perspective. Too many people get caught up on only Wii vs. Xbox360 vs. PS3 and simply compare them all straight off the bat.
You have to look at it objectively. Not to mention the Wii is taking a very different direction towards it's internet. Unlike the other consoles it can connect directly to the WWW while the others run through services like Xbox Live. It really is never as simple as you think espcially when you decide to take a new road.