Adding stretch goals sounds like a good idea, at first, but I'd rather see extra attention to detail on the core game.
I'm certain that a financial success of this magnitude will yield expansions and DLC in the future - possibly crowd funded - and I don't feel that good ideas will be lost to eternity (ahem) because they weren't included in the original game.
I do think the poll options are poorly worded - the second option should have been "No, I'd rather Obsidian concentrate on quality. I'd consider funding future expansions or episodes once PoE is released." and a third option could have been "No, the promised game is enough forever."
