I think the problem is, that nobody really knows what had happened if we've let the banks die.
The fear that the results might be a lot worse than the current situation is perhaps the driving force of politics of the last years.
That sounds a bit like only risk-taking share holders would have been harmed and that wouldn't be much harm for the society at all.
I really don't think that the harm would be that focused, because banks aren't only about risk-taking share holders and because of the interconnection of banks at the end someone might be harmed you've never thought about.
I really don't envy any politician having to make a decision in such a case.
I'm not even an economist, so obviously I have no idea what would have happened (even as is in "they don't really know" but I know even less).
My reasoning is this: if I remember correctly Greek government bonds were already trading at ~70% of their nominal values two or even three years ago (cannot check, currently on a train along the Rhine with very limited internet access). To me this means, that the banks had already written off ~30 of the value of that bonds, and I bet if we look at their balance sheets we'll see that fact reflected.
I called my local elected representative about it, SPD (social democrat), and "voiced my concern", but only got met with talk about chain reactions and responsibility. Perhaps I shouldn't have shouted.