Part of it is that I feel like I've seen enough cruelty and evil triumphant in the real flesh and blood world I move through every day. From petty, small viciousness to boorish rudeness all the way up the ladder, with stops at knee-jerk offense for offense's sake, lying, stealing, racism, sexism, and it just keeps going up and up and up. I don't play World of Warcraft or other games to revel in that kind of behavior, because I see entirely too much of it (and worse) in my day to day. I play the game to escape those things, for at least a little while.
Now, I'm neither arrogant nor self-centered enough to demand that the game be tailored to me, or conform to this tendency. I get that there's a catharsis inherent in playing the black hat for some folks. I even get that there are shades of grey and interesting challenges to be had in coming up with reasons and motivations for people doing the worst things. Conflict helps create interesting stories, and you can't have conflict without opposition. I get all that. But I admit, I'm still rendered somewhat uncomfortable by people who get excited about evil, who use terms like deliciously wicked - in my experience, evil is far more often banal and tedious, wickedness usually the work of dull, plodding and inflexible minds.
Therefore, I'm surprised to find myself sympathizing more and more with Garrosh Hellscream as this expansion has unfolded.