ET3D: Most of them aren't backers, many don't think much of Kickstarter in general, and they just see it as a way to say "I told you so" (or something like that, since they mostly didn't tell us so). These people don't care much about what's really happening, and don't have anything productive to add to the discussion. They're basically trolls.
No, many of the non-backers are people concerned that this is the way that game development is going to become in the long run, although I personally am of the conviction that the Kickstarter model will fall apart of its own volition on the back of fuck-ups like this. There's a reason people like me don't back crowdfunding projects.
Not to mention there have been plenty of people who have criticised Double Fine's actions, also having backed Broken Age.
And some people just don't like watching other people get screwed over, especially when a situation looks so dubious as the Double Fine Kickstarter did. Sue me - I'm a sucker for honesty. If that makes me a troll, fine. If I'm saying "I told you so", it's not because I get some bizarre sadistic pleasure out of it. It's because I'm saying "next time people say that things don't smell right, you'd do well to listen to them instead of labelling them trolls and diving in where angels fear to tread".
ET3D: Some are backers who didn't really follow the process, didn't watch the latest episode of the documentary, and are mainly fed off what's being posted. They are generally dissatisfied because they're lacking information they can get, and sometimes partly because they had an unrealistic view of what's going to happen (such as imagining that they will get the game on the originally estimated date).
Ah yes, the fanboy argument of choice, quoted word for word - in other words, "we have information that you don't so anyone who dares criticise is automatically wrong".
"Asking a publisher for the money was out of the question because it would violate the spirit of the Kickstarter, and also, publishers. Going back to Kickstarter for it seemed wrong. Clearly, any overages were going to have to be paid by Double Fine, with our own money from the sales of our other games. That actually makes a lot of sense and we feel good about it. We have been making more money since we began self-publishing our games, but unfortunately it still would not be enough."
They had the $3.3 million from the Kickstarter, the money from the tip jar, the proceeds from the sales of the games (including the Humble Bundle), and whatever money later backers have donated. I'm not exactly sure what's possible to take out of context. He quite clearly said he's concerned that he doesn't have enough money to finish the project because he "designed too much game". He admitted it was his own fault. The admission is praiseworthy, but it doesn't answer the question "what now"?
Fanboys are going on about how we are "missing context". Fine, the ball is in your (collective) court. Enlighten us - tell us why Double Fine went from budgeting a $3 million game into having barely completed half of it with a release date delayed two years beyond its scheduled release.