Thats a bad idea. If a Wii console has hardware capable of doing good graphics for ANYONE, then every man and his dog will be making Unreal Engine 3 games for it. Its completely against their policy of exclusive long running franchises with naive fan bases that will viscously defend the games and spend as much money as told to, even for straight ports.
By keeping the hardware a pile of shit and beetle husks, they ensure the only people releasing quality games for it are the ones that have taken the time and commitment to learn to get actually good graphics out of it, usually people so deep into their Nintendo contracts they can't really get around it. See, if all the games on Wii looked passable, would Metroid Prime 3 turn any heads with its actually pretty graphics? No!
All the rest are forced to come up with Wiimote specific gimmicks since they can't just add ragdoll and explosions and motion blur to everything.
THIS IS HOW NINTENDO GETS RICH SOMEHOW DX