In terms of Wii owners, that won`t change anything for those who never played the game, but for those who are coming from Xbox 360 and PS3, it will mean less Wii U ME3 copies sold as they can play 3 games instead of just one, even if that one was a special version.
I think EA could have done a better job with porting the series to Wii U.
It would be troublesome to have three games ported to Wii U, but most of the trouble seems, to me at least, to be about the controller adaptation. A port for ME3 is already on it`s way, someone is already porting the first one to PS3 - and a Wii U version could have been done at the same time.
The Wii U trilogy could have waited a bit longer to get released but putting out a trilogy for your average price on a console that is building a fanbase and probably with a lot of people who never touched the series, would be a good incentive to make people buy the game.
Personally i`m still thinking seriously about buying the game, but with 3 games for the price of one, who could resist?