What I find fascinating about vilains is that, once you overlook the abuse and ''evil'' they do, you realize they are not so different from the ''good guys''. They were, many of them, hurted or treated with unfairness (as in the case of Scar, who WAS indeed at a much better chance of earning the throne before Simba came along), but, instead of accepting their fate, they actually DECIDED to do something about it (even if it meant killing people or ruining another's life). For example, Syndrome in The Incredibles was originally just another boy (Buddy Pine) fascinated by his hero and wanting to help him. But Mr.Incredible coldly refused him, making Buddy positively hurt and it enraged him so much to be rejected, that he decided to TAKE ACTION and CHANGE THE RULE(You cannot become a superhero if you are not born with a power), by killing of every real super and becoming the great superhero he wanted to be. AND, not only that, he actually wanted to make a sort of ''reverse revange to not only Mr.Incredible but to all the future supers as well, by making their powers available to the public. So, by the time, a super actually embraces his destiny, the general public will go ''A superhero? Pfft, I've seen better.''
Syndrome is one brilliant vilain, indeed.But, anyway, my point is,vilains are essential ordinary people who were so hurt they basically went ''So, you're being unfair to me? You're hurting me? Watch how that feels!'' *POW, POW*
Another thing interesting to point out, is that, at least in the Disney Universe, almost all of the rule breakers gets punished (if not murdered accidently or on purpose) for trying to break the ''holy rule'' (like, Ursula gets bannished for trying to take over the throne, but what if she had good ideas (aside from revenge?) Jafar tries to become ruler instead of letting a rather incompetent-looking sultan do it) Or, even Forte (BEAUTY AND THE BEAST, AN ENCHANTED CHRISTMAS), all he really wants is not to loose the only one (The Beast) who pays attention to him.). Just for trying (perhaps, in a gruesome way) to get some respect or a right they lost, they are immediatly wiped out. So, the subtext of many Disney movies is ''Never break the law or disrespect the authority, even it treats you unfairly. If you question it, you are not Worth living.''
To conclude, as Syndrome himself said: '' See? Now you respect me, because I'm a threat. That's the way it works. Turns out there are lots of people, whole countries, that want respect, and will pay through the nose to get it.''