"but I don't think that explains nearly the volume of them we're seeing"
That's just because the most popular system ALWAYS gets the most shovelware, back to the 2600 days (just Nintendo managed to avoid those crashing the NES).
With the Wii, it's about ratio, and that is because developers were resistant to support the Wii with their big games, not because of easy money. Making AAA games for the Wii is also easy money, as it means those games don't cost as much, but still sell (just long term instead of up front). Many developers just refused to see that until recently.
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








