I can cite many examples of people who have abandoned PC gaming for XBLA, PSN, Wiiware, Flash gaming, Unity web gaming, or the iPhone, I don't know of a single guy who has jumped onto Facebook. So the fundamental thesis of hardcore indie developers being tempted by the lucrative cash piles to be had in Facebook apps seems pretty dubious.
The other contrarian point I'd like to make is that Facebook has actually been really kind to indie developers. Facebook Pages are huge for self promotion: Facebook is consistently a top referrer for our game, even though it is a traditional, PC/Mac/Linux downloadable game (that's not even released yet).