The way I see it, the overall setup looks like this:
[capital] <--> [financial system] <--> [projects]
So basically the role of the financial system is to (i) allocate capital and (ii) manage risk. I think it is totally clear that the financial system failed with the latter, but where is the evidence that it failed with the former? With the "subprime loans" were the houses that were built shoddy? It's not like as a world or nation we went out and built some giant white elephant that is now useless. By and large the projects funded remain sound. The problem is that the financial system has seized up.
A few folks have suggested that rather than pumping several trillion of new capital to save the existing disfunctional financial system, we should just pick 20 banks out of bankruptcy, capitalize them and basically replace the existing financial system with a new one (and then distribute the shares in these banks to all citizens so it's not a government run thing).
Bottom line, the financial system is broken, but I'm not sure the fundamental underlying "projects" are themselves broken.