From my perspective, the root cause of what happened is that no one anticipated an event that would simultaneously cause failures in multiple systems (power loss, and destroy probably multiple redundant generators). It's easy to say after the fact that of course someone should have thought about that, in your words they should have had "better advisors", but I'm not sure how useful it is. All nuclear accidents that I'm familiar with were unanticipated. Can anyone really argue that they all just had bad advisors or engineers?
To me, this is the real argument against nuclear power and I say this as someone who still thinks that overall it's a good idea. How can we say something is truly safe when the accidents that did happen were not anticipated?