Thats kind of the problem with the stretch goals. It just makes the development even more difficult and the wait longer a lot of the times because more money doesn't always mean you can work faster.
No, the budget was 400k. In what bizzaro world does 750% more funding delay project completion by five months? Just because you have extra money doesn't mean you should expand your budget to max out all your resources; try that excuse with any VC and tell me how it goes. Fortunately for Double Fine they're not actually responsible for how they spend their money.
I understand where you're coming from, but I don't think that if Double Fine took the $3.3 million and delivered a 2D, mobile, prototype-esque game (which if you watched the documentary, was what they would have gone for with the $400,000) in the timeline they stated, people would have been happy.
It's exactly like they took the $2.9 million and ran. I think quite a lot of people would call that a scam at that point. In the end, with an extra $2.9 million, what were they going to do with it other than make sure that the game they end up delivering lives up to the huge sum that their fans gave them?
The budget was 400k for the basic version, then they got 3.3m and changed the scope. So 3.3m was the new budget, or perhaps some number in between and the difference was pure profit.
Oh, and also, backers do get tons of content all the time.