This actually makes me less willing to contribute. The worst outcome here is that they hit 15% of their funding goal and get stuck there, which means that there's enough money to do some work and to raise expectations of results from the funders, but not enough to produce a commercial (or near-commercial) quality game at the end of it.

With a Kickstarter all-or-nothing approach I can be quite generous (I'd probably go for the $100+ option here), safe in the knowledge that if nobody else offers any funding then I won't be the only one chipping in.