I don't disagree with the general sentiment that the GFC was a total disaster, and I'd certainly not argue against the idea that a system had developed that had poor incentives, with sometimes greedy and unethical people working in it. What kind of concerns me, though, is the way that poor decision-making is conflated with breaking the law, or the belief that a terrible outcome ex-post necessarily implies illegality. I don't really see this logic being applied in other walks of life - in most jobs, if you are incompetent, or even incompetent and amoral, you wouldn't expect to be prosecuted.
For the most part I'd not see the GFC as a morality tale but rather a kind of weird emergent phenomena whereby one area of the economy became so big and complex that it was beyond's anyone's ability to manage, and the interactions of the millions of bit players in it - all of whom in their own way wanted to succeed and do well for themselves - led to this collectively disastrous outcome.
Which isn't to say that nothing illegal occurred - I'm not sure how you'd draw a boundary around the GFC but there were a number of securities fraud prosecutions in the years afterwards - but I think if you take the GFC and subtract all illegal behaviour, you'd still have the GFC.