Also when I think 'cool', it's not so much in line with 'badass' as it is being threatening, powerful (within reason for the story), seemingly untouchable for a time, darkly funny, and in control. Often, for me, this comes to mind:
The prequels killed any cool he had. Deep down, he is now that whiny Anakin who dropped his allegiance and killed everyone on pretty much a whim. Before you could think of some cool backstory in your head that would make his fall seem tragic, but nope, he is just a dumb whiny asshole.