What self-respecting villain would miss an opportunity for monologue? The silent type exists, but usually they end up being lackeys for gloating masters. Example, Darth Maul.
And heck, I'd say Darth Maul isn't a real villain anyway. Sure, he looks like some sort of demon, and he attacks the heroes, as they are his enemies. But in the grand scheme of things, I see nothing that he's done that's more evil than what the good guys did.
The monologue is what sets the Evil Villain apart from the mere enemy. The enemy is probably not a bad guy and you could probably get along fine with him in other circumstances, but there's a conflict and he's on the other side. The Evil Villain use his monologue to assert that he's really an egoistic, sadistic jerk that wants to be a pain in the behind of everybody just because. By demonstrating his evilness for all to see, he helps justifying the good guys' actions. And this justification is what let them be heroes, rather than psychotic murdering burglars.
'Cause, honestly, what would you say about a bunch of violent, armed misfits who trespass on somebody else's property, kill the owner as well as his employees and bodyguards, loot the corpses, pillage and vandalize the property, and then come back to sell the acquired loot to pawnshops?