I guess you're right, whether you've played all the ME games or just ME3, it doesn't make **** all difference to the ending cause it'll still suck either way.
It's stupid because I know the Nintendo-only console gamer and they're a different kind of fanbase than what you'd find with the PS3, 360 and PC base. Basically very few people will buy ME3 because it's not a game that was "made for Nintendo"... there's a really strange reasoning that goes behind it, but basically if fans know that a game is made for a Nintendo console, they'll buy it like hotcakes, even if the game is really terrible like Red Steel. Ubisoft basically said "we're making a game just for you guys" and everyone bought it while all of the Call of Duty ports end up bombing and get thrown into the bargain bin cause no one plays them.
You're right, it is a smart idea in that BioWare is making a really cheap cash grab, but it's still stupid.
Arkham City I feel is a better fit but they tried to show it off as a game that would BRING people to Wii U, they were trying to demonstrate the game is better on Wii U and you should buy one. Where are they trying bring them from, platforms where they have already played the game?
Assassin's Creed 3 on the other hand is the best to represent multiplatform titles on Wii U... it hasn't been released yet and while it may be the latest in a pretty long series now, Ubisoft can easily release the previous AC games on Wii U for a budget price much like Capcom did with the entire Resident Evil series on the GameCube. Out of the three, Ubisoft is making the smartest move. Not only are they introducing Assassin's Creed to the Nintendo gamer with the ability of porting the previous games to Wii U if they choose, but they also have ZombiU in the works which is a "made for Nintendo" game... BioWare = stupid. Ubisoft = smart.
EDIT: oh, and let's face it, without all of the references to things that happened in the previous games and all that we experiences, ME3 is just ends up being a mindless action movie with a crappy ending... I mean even more so than it is to us, the people who have played the other games.