The problem isn't that you can't make a complex game like Bioshock on the Wii. The problem is if you design a game like Bioshock to make full use of Xbox 360 or PS3 hardware porting to the Wii isn't possible without a buttload of work scaling it down.
The article though talks about the Wii audience as if EVERYONE who owns a Wii is some inexperienced non-gamer. The 2K Boston guy says "It seems like, on the Wii, there's some education necessary for a large part of that demographic, in terms of, 'Here's why you should want to play this game, instead of Wii Fit.'"
This is where the whole "us vs. them" thing comes from. By focusing so much on non-gamers Nintendo has screwed us out of decent third party support because everyone thinks the whole userbase is Carnival Games buyers. So all these first party core gamer games (that are all token sequels) don't make a difference because the third parties see non-gamer JUNK selling and assume that that's the whole Wii userbase. It's no different then when Nintendo was kid-e and was doing jack sh!t to remove that image and sure enough the third party support was inferior because of it. Nintendo focusing on non-gamer stuff at E3 says "this is a non-gamer console" and it doesn't make a difference how many core games they make because the image they project pigeonholes their console.
When I read a blurb like this where the developer seems quite interested in the Wii but is still making blanket "lol casualtendo!" statements I start thinking that there can't be a console that's for both non-gamers and gamers. The two groups are too different and that's why we've got the PS3/X360 getting all the complex core gamer third party games while the Wii gets junk, despite being the market leader.