Q was never a villain. He was an ANTAGONIST (and no, the terms are not one and the same). Villains can be - and generally are - antagonists, but not all antagonists are villainous.
Starbuck: We're all friendlies. So, let's just... be friendly.
"There is no 'supposed to be.' It's an adaptation, a word that literally means change. Why bother making a new version if it doesn't offer a fresh approach?" - Christopher L. Bennett