"That doesn't mean it should be a rule that Wii games have smaller marketing budgets though"
It's not a "rule". SD games that aren't huge releases tend to get relatively small marketing budgets, so even though they sell less, they still make a profit. This isn't just the Wii. It applies to any SD system.
A flashy-first game is awesome when it comes out. A great-first game is awesome forever.
Plus, just for the hell of it: Kelly Brook at the 2008 BAFTAs