It's impossible to say how this trend will work long term but I suspect a lot of the open source software I love today wouldn't exist if it had relied upon raising $50k up front.. not only because of the likelihood of raising the cash but because the lesser extrinsic motivation suggests, perhaps, that there was more intrinsic motivation for developing and releasing those projects?
I think it's great if proven projects take donations or sponsorship to kick things up another notch or to support full time developers, but merely to start a project? I'm on the fence about that, and will be interested to see how it plays out as a model.