You need to make good games that can fit cleanly into the types of genres that are/have historically been popular in the US/the world. Platformers, FPSes, fighting games, racing games, action/adventure games...things like that.
Rail-shooters, point-and-click adventure games, shoot-em-ups, quirky Japanese games, puzzle games, et al...while those can be (and have been) very good games, those aren't going to be the games that set the US marketplace on fire, and they never will.
You need to design them with real effort. Maybe you don't have to code to the metal anymore, but the game should be able to look and sound better than PS2 games. There is no excuse for games to look like games from 2001 in 2010.
You need to put your better teams behind those games. Why can't EA's top teams make games like their HD counterparts on the Wii? Why couldn't Ubi's? Why can't Activision's?
You need to show real faith in them, and provide legit advertising/marketing support. They put real muscle behind advertising even unknown things like Borderlands and Darksiders, and those were untested new IPs. When something like Red Steel 2 or No More Heroes 2 comes out, are they going to blanket the airwaves and magazines/stores with ads for them?
You need to avoid making "test games" or late ports of things. No, you are not going to sell boatloads of Call of Duty: MW1 Reflex on Wii when it is a port of a 3-year old game that isn't even being advertised. No one cares anymore. No, you aren't going to sell boatloads of Dead Space: Extraction when it is a late spinoff railshooter version of a not-so-popular, relatively new/unknown game franchise that didn't even do good numbers when it was a new game on HD consoles. It will especially not do well when it isn't advertised either.
Third parties want to sell Crystal Chronicles on Wii, and both the casuals and hardcore only really care about real Final Fantasy. I bet you if Versus XIII came out on Wii, it'd sell a fuckload. In fact, I bet you if even FF XII International was ported to Wii, it'd sell better than Crystal Chronicles. Just show some effort and goodwill towards the Wii consumer base, and it will probably respond.