Steam is already fairly lax on the 2 hour period for refunds if it's close. The system is in place for those terrible games, like probably 70% of the indie games on the steam store, that look decent but are buggy, unfinished, messes. And for when you buy a dumb game on an impulse for the 5 minutes of "lOL so RANdom Xd" and then instantly regret it.
~2 hours, or 2 weeks, is really fair for you being able to think that you shouldn't have bought that game.