TvC was MUCH worse than Brawl, service-wise. You don't have to be a tournament-level fighter to realize that lag and Shoryuken command inputs don't mix. Plus it's a LOT harder to excuse in one-on-one connections. In my experience Brawl usually holds up well until the fourth person enters.
And I don't have a problem with lacking identity in karts, I'm content to simply be that random Yoshi/Daisy player with an obscure Saturday Night Live name reference. I have a problem with the grand item farking, which is not a complaint one would expect an all-Bob-omb Brawler to make, but in kart every damn time you turn around someone hit a POW block/Blooper/Lightning/any of the two-dozen ways to make you drop your items. There's a ludicrously excessive amount of "hit everyone" and "disarm" going on, which I sincerely hope they cut down on for Kart 3DS.
Thing is, TvsC was essencially attempting to be a serious fighter, while Brawl is a fun party game that people [sonic slicer] about not being able to play seriously. I'm fine with fighter game lag on Brawl. All fighting games have online lag. But the game itself was coded online SO BADLY, it was probably one of the very worst online modes I have ever seen in any game whatsoever.
And in terms of Mario Kart, you and other people may not know this, but it was the first Wii game that got to the point of having... well, a mediocre online system which every single XBox/360/PS3 game had so far. The normal required options, the modes, and the necessary speed to play. At this time, anyone else used to regular online gameplay wasn't pleasantly surprised. I just went "Really? Oh, that's cool, I guess". Identities are really important in online games these days. Having a profile, having an actual way to see what kind of games you play, to be able to play with that person again...
I hate the fact that Nintendo's multiplayer is basically ChatRoulette.