If you give PCs a chance to have dramatic last words, it's only fair that you give significant NPCs that chance too. Use their last words to set up or reveal something that the players never knew or even suspected about their foes and their evil plans.
Make it so that later on they will want to have kept the villain alive.
In fact, this is a generally good idea. If the PCs kill someone or destroy something, make it turn out to be important for them later on.
With any luck, the PCs will get so paranoid that they'll stop killing bad guys. And then of course you can have them escape and cause even more problems later on. Win-win!
Palpatine: Oh dear; Anakin, please see to his wounds and check on Obi-Wan.
Palpatine: Count Dookû, I am sorry it has come to this.
Count Dookû: You 'ave betrayed ze entire Republic. Ah spit on your sympathy.
Anakin: No more of your lies. No wonder the Senate wouldn't listen to you.
Count Dookû: Ze Senate is, 'ow you say... ze zhuggernaut of futility. It 'as been corrupted beyond redemption.
Anakin: How dare you accuse Senator Amidala! She has honour, grace, and compassion - qualities you have discarded.
Count Dookû: Your Zhedi Masters are tainted too now.
Count Dookû: Ze entire Galaxy is doomed.
Anakin: It's in good hands. Palpatine will lead us to a new era of prosperity.
Count Dookû: Even ze Separatists 'ave betrayed moi. Ah feel nothing but blackness in my 'eart for ze death and sorrow to come.
Anakin: You have fallen to the Dark Side.
Count Dookû: And... Sacrebleu!
Count Dookû: Ze Peace Moon plans! Nute Gunray, 'e must 'ave switched zem!
Count Dookû: Ah am truly alone against zis tide of evil.
R2-D2: So we're the bad guys now? Cool!