But what you aren't seeing is that this entire problem has a relatively simple solution that doesn't involve a big government bailout (and notice I said relatively simple not just simple). The banks that made the bad sub-prime loans need to sit down with the people either in foreclosure or close to it and restructure the loans. They need to make these loans easier for people to pay, make them affordable even if it means extending the term of the loan 80-100 years. If they do that then the banks will once again have money coming in that they can count on and use to make other loans. Yes the payments won't be as high as they had originally anticipated but having a little money coming in is better than none at all and/or a house that you can't sell.
You.... don't seem to understand the problem.
It's not the mortgage themselves that launched the nuke on the markets, it's the commercial papers. It's a derivative products based on the different mortgage. For example, if I wanted to invest (me, a small peticular) into people's debt, I might have bought commercial papers from Bank Y. Bank Y that way load off the debt people contracted to it by selling it to somebody else. In theory, that was fine (and a darned good idea, since it allows Bank Y to allow more credit, but let's come back later).
The problem is, people who bought those derivative on debt expected some good return on their investment. When the house bubble popped, many people couldn't repay their mortgage. It's not Bank Y who suffered the brunt of the popping, but the people like me who invested in those commercial paper. I effectively accepted to bear the risk of the mortgage default. (I agree with many people that the financial sector has been reckless with those financial products. I'll explain it at the end of my post). So, even if Bank Y re-negociate the mortgage with their failling customers, the people who invested in derivative debt are still screwed hard, since what they bought just lost a lot of value (a LOT).
It gets worse. A derivative on debt was effectively considered debt for asset allocation on many investment firm/bank, so they used a lot of those assets to cover their own lending. Why? because debt is supposed to be "safe", specially when you invest in AAA-grade debt. But now, many people lost a lot of money and companies are having the domino effect I am showing up-there.
The worst action Wall Street took was to rate the quality of derivative product based on the bank that emmited them, and not the base-mortgage. If Bank Y (with a perfect rating of AAA) accepted to mortgage to someone who just got out of jailed, have a lot of financial problem, etc.. etc... because the interest rates were awesomely low (thank you, Fed 2002), then the derivative products on that mortgage would have been rated... AAA. And not as a "junk debt" as it should have been. There have been some SERIOUS wrong-doing in that peticular case, and I seriously hope we do something about those rating firm in the future.