We were actually considering adding a checkbox for allowing the project to keep the money even if it wasn't successful, but the boss said no as it would apparently give a bad impression to backers. I don't really understand why that would be so, though.
The point of fundraising is to get enough money to have the game made instead of not made (or otherwise affect the development in a meaningful way).
Suppose a game asks for $100k. Even assuming good faith on the part of the project creator, if the project is currently sitting at $0, I have absolutely no incentive to donate to it UNLESS it's just taking preorders (as Grimoire does, and even then Clive is dumbwrong for giving IndieGoGo a 9% cut).
In 2009, successful kickstarter projects asked for sums like $100 and $200, and no, I didn't leave out zeroes. It was understood that those were basically epic-long-term, sky-high-risk preorders, the game was being made anyway, and the money collected did *not* accelerate development much. But to attract big money, you need to promise to deliver a game of a particular quality within a reasonable timeframe. You are assumed to have set the minimum goal to satisfy these criteria.
If a project asks for $100k to release Tehpwnzor McAwesome the game
* by Dec 2013 and collects only $1k, it has no business keeping that $1k unless the donors were actually willing to wait well into the next century.
*I'm working on it. No project, though.