Even if I had an idea which I could self fund, I would still consider applying to Y Combinator, as the experience and networking you would receive would definitely benefit a project greatly.
The only thing that gets on my wick a bit about Kick-starter is that the funders essentially get nothing (other than see the product get created). I.E. This product could go on to be valued at millions and you're initial $1000 contribution to the seed funding would be unrewarded.
True (and good point), but they also don't get the benefits of the mentorship, the alumni & mentor connections, and the shared drive of being with 10 other groups doing the same thing.
At least, that's what Kickstarter sort of proposes with their model.