Typically, science fiction conventions will offer a panel discussion on villains (and also on heroes, but more along the lines of how to make them less... boring, to put it frankly). Writers and readers love to talk about the bad guys. After all, more often than not, they're more interesting -- not to mention sexier -- than the good guys. Of course they're attractive. They're dark, dangerous, edgy -- in other words, forbidden fruit. Even Jane Austen's naughty boys have a certain intoxicating allure.
Bad guys are also more likely to be complex in interesting, tortured ways, and to be charismatic and cunning, but with fatal flaws that prevent them from being heroes. They possess the capacity for grandeur, except for... But you know all this. You've read the rewrites of classics told from the point of view of the villain. You know every villain is a hero in his own story, it's just that his goals don't align with those of the protagonist, but none of them get up in the morning and say, "Evil! Evil! Rah-rah-rah!"
I've been thinking about why we keep coming back to having villains, as distinct from flawed heroes or misunderstood monsters, in our stories. Aha, you say, to provide conflict, to place obstacles between the hero and his goals. Sure, you say, because there are really only three plots: Man Against Nature, Man Against Man, and Man Against Himself. (I think this is an oversimplification, and I'm not at all sure it's true, but the point is that conflict
between characters is one of the enduring themes in story-telling.) Once upon a time, all you had to do was put a man on a black horse or in a black hat, give him a mustache and a name with too many consonants, and everyone would understand that he had no redeeming qualities (and bad dentition). Later, it became desirable to give him a few aspects to admire, and to play around with expectations. Then it became fashionable to portray him as not-really-bad, but wounded or misinformed or warped by his culture. Science fiction and fantasy, not to mention the whole of English literature, abounds in examples.