Show me any game ported from normal consoles to Wii and tell me it hasn't suffered a huge drop in quality (not counting RE4, of course).
What about Godfather: The Game, Harry Potter and the Order of the Phoenix, and Okami? They didn't suffer too much critic-wise...
The problem is not the Wii when games from other platforms suck on it. It's because the developers are too lazy to come up with intuitive or working motion controls and compatible user interface and just shove it onto the shelves without further polishing. Tiger Woods 07's menus were completely unsuitable for the Remote pointer, and the motion controls when swinging were clunky and erratic.
Me, I prefer the Wii's motion controls in games. I love the experience.