Ignorance, disconnection and complete negligence. Yes, my point exactly.
They were completely and woefully incapable of dealing with the real threats against them, and in fact created one of them, because they were no longer true to what they were meant to be.
Don't get me wrong, Sidious is a monster and absolutely deserves blame. And Order 66 is the kind of genocidal nonsense that marks anybody as evil. I'm not trying to argue that the Jedi were evil, not at all.
But the films are thematically predicated on the premise that the old order had lost it's way, and Luke helped right the ship by ignoring Yoda and Obi-Wan when they told him how to be a Jedi vis a vis Vader.