I mean, they're still the same person, and they don't have to pick random targets. Makes for a more satisfying bad-guy/villain experience for me, and I hope so for others, when the motives are something other than simple body-count, or power for the sake of power. Why do they want that power? Maybe they saw what happens when other bad-guys get the power first. Perhaps they didn't even want that level of significance, content to lead a humble servant's existence, but see it as their duty to insure that someone more dirty than them cannot have it, because we all remember the last time this sort of thing happened. Perhaps those around them know it, so excuse the occassional wickedness or deviant behavior as necessary to prevent future tragedy.
There are plenty of very good reasons for good guys to do bad things. It makes for an interesting internal experience when they have to live with the knowlege of what they've done, and alternate in their ambivalence toward the act that was a very good, bad thing to do. Eventually, it all goes grey and balances out. This is the essence of beneficial corruption, when one isn't focused merely on corrupting others, having the knowlege that they also corrupt themselves. This is also the point where your god possibly revokes your cleric powers, and just maybe smites you with fire from heaven. Whoops.
So, is there room for kindness? Absolutely, so long as it's not suicidal, or doesn't jeopardize the greater good. Reckless acts of kindness are, not sustainable or realistic. Sometimes the greater kindness is, in the short term, seemingly cruel acts, even torture, murder, betrayal, dishonesty... I am of the opinion that absolutes are bonkers, that moral polarity is unreasonable. Your milage may vary.