Stanza
Lighthouse Keeper
Generally, I find that those who want to play evil seem to be deeper into the role-playing aspect.
I don't know about that one. You'd really need to identify what type of "evil" you're talking about. In discussions on various boards, it usually boils down to two main types of evil: the subtle manipulator, and Bioware's petulant adolescent.
The evil manipulator role allows you to trick NPCs into doing things, relies on deception, and is pretty well personified as a Moriarty-type character. Your character may even be perceived as "good" while you're sowing the seeds of evil. It's something that heavily relies on dialog, is hard to define, hard to implement, and almost never seen in RPGs. This is the one RPG fans often dream of, but we seldom get more than brief touches of it.
The other standard category of "evil" is the personification of Bioware: threaten people, make smart-arse remarks, and alternately act like a dimwitted street thug or out-of-control adolescent. It's an approach that certainly appeals to younger gamers, but it turns stale real quick.
I dislike the "evil" options in games, but that's because most of the games that offer "evil" options are either from Bioware, or follow close in the Bioware design. If the game gives me the option to act like a hero or a jerk, I'll pick hero every time.
But if someone makes a good Moriarty game, I'll definitely play it.