I think you're undervaluing everything that Kickstarter adds in terms of a platform (collecting payments, notifications, social sharing, brand awareness for the platform itself that breeds trust, etc.). Kickstarter takes a small 5% percent of the total successfully raised.

For a documentary film or artist recording an album, it wouldn't make sense to yank your project and try to crowdfund on your own. In the case of Mod/Draft it was an MVP and they're shaping the offering differently -- notice that they were thinking of relaunching the Kickstarter.