Which we're all familiar with that in game development and game purchasing, for sure.
But when you've set up those expectations by asking for people's money, it takes on an entirely different tone and meaning.
And then you have the eccentric millionaire problem: Let's say you're making an RTS or TBS, a very standard one. People pay in, they want their units and what not....but then some guy comes in, dumps some serious cash into your project and says "I want [system totally unrelated to RTS and TBS gaming] in your game. And I've paid to have that expectation fulfilled."
What then? Cave to the wishes of your biggest supporter? Calmly explained to them that any requests paid for still have to respect your development wishes? Rethink your design to accommodate someone else's model? Do the same thing on case-by-case basis with anyone that chips in?
Creative freedom is the freedom to say "no" more than it is the freedom to say "yes", to me. And it feels like one of the first things lost with this model, and is at odds with how the model runs best (saying "yes" as much as you can to generate more investment.)
The way I see this model working best is with indie developers who don't have serious salary requirements and teams. The kind of team that still has 9 - 5's to make their house payments. Because they can always keep working with zero investment, if they started for love and not money. Once you have a budget and people rely on those donations to live....you get forced into making ugly choices, and saying yes even if you don't want to.
I do see this working in some ways for smaller teams. You have your donation link up there and you say "Anyone that donates any amount is buying a full copy of the game when it's released." You don't rely on their donations, but you are fueled by them. Once the game reaches completion, you say "Very soon we will be taking down the donation link. Any donation made up to that point still gets you the full game. Once the donation link goes down, the game is purchasable at its market price." People look at what you've got so far, you get a nice revenue bump just before the link goes down, and then you move on to a standard release model."
I know this doesn't work for the scope of a lot of games people want to make...but these days the stuff a small competent team can produce in anonymity is just looking better and better, and more interesting, than these multi-million dollar games with high price tags. I already support a few games like this, Dwarf Fortress being one.
In a perfect world, this model would be almost a charitable thing done by gamers, where we give to video games purely so they can grow. But gamers are inherently self-centered I think, to a degree. We're interested in our experience, our fun, our group's fun, our communities' fun. Our interest in gaming is selfish because it's entertainment more than art (despite the fact the US government officially recognizes games as art.) So grappling with what gamers want vs. what you want vs. the fact development relies on support just leaves me with cold feet on this one. At a rate of $1, I'm not that bothered. That's charity, and $1 x 30,000 is still $30,000. But much beyond that and it turns into gambling from my perspective.