The short answer: because it’s actually pretty tough to do evil well. Most people end up being “Evil.” (More on that below.)
Evil done well:
(Gul Dukat, “Deep Space Nine”) – If the guy who ran Auschwitz believed himself to be the ‘kinder, gentler’ administrator who prided himself on reducing deaths by 20% during his tenure, and wanted to be loved as an overlord. And if that wasn’t bad enough, he then becomes the footsoldier of the Jewish Devil and swears to kill every Jew. But between the start and end of this character’s journey, we see him as a father, a leader, a patriot, and an insidiously evil manipulator who deserved his final end.
(Crais and Scorpius, “Farscape”) – Crais, the man Captain Ahab would be if he lived in space and someone had killed his brother, willing to kill his own subordinates to keep chasing John Chrichton, his ‘whale’.
And Scorpius… the ultimate, “The Ends Justify the Means” evil mad scientist who has no problems with murder, torture, making/using weapons of mass destruction, or genocide, as long as it’s pointed the right direction.
All three of these characters are evil characters that are fan favorites and end up working together with the heroes in particular situations when common interests align. They have a lot of depth, and getting these characters from the page to the screen took a lot of hard work, incredible acting, and a lot of trust between the performers… which are all the same tools needed at the table.
What is evil?
Definition – Evil: profoundly immoral and wicked.
Evil is not something that tends to play well with others. D&D is a group game that is between the Dungeon Master and the Players; there has to be cooperation between all parties involved to have a game.
The problem with many players trying to play evil characters, is that true evil doesn’t lend itself to cooperation.
For instance, a classic bar for morality would be something like, “The Ten Commandments” from Judaism/Christianity. So being immoral would be doing the opposite of these commands.
So what does a player do in a campaign to be “immoral”? Probably lie, cheat, steal, and maybe torture or kill. And to be frank, that makes many people uncomfortable to watch, and it’s worse when the target of these acts can be the other PC’s.
This is a major reason why there are three alignments for evil, including “Lawful Evil” in D&D. LE in particular helps define someone who is okay with doing immoral things as long as they are justified by law or order. Sometimes this makes a shared road, (law and order) that can be shared with the good guys of a team.
That doesn’t make the whole problem better, by the way, it just gives more wiggle room for an evil character not to butt heads with the party quite so much. “I wouldn’t steal from you or kill you because we’re on the same side. But I’ll string up my enemies and dance in their skins because they are my enemies, and that’s how our law says we treat them!”
Now, before everyone starts loading up the comments area with “But!” and “IF!” statements on how they played an evil character in their campaign and it was totally awesome, let me remind you that I’m talking in general. A lot of people DO NOT play evil well, because they play “Evil”.
“Evil” (in quotes, I told you I’d come back to this) is a player’s preconceived idea of what they want their evil character to be. Some people call this “Emo”, or “Edgelord”, or any number of other things, but the key here is that it’s an idealized version of what evil is or supposed to be, and being played in one of three ways: a caricature of evil, (the mustache twirling villain), the chaos craver, (the person who just wants permission to do whatever they want, whenever they want, without morality being an issue), or the selfish jerk, who basically is playing only to gratify themselves, even at the expense of the other players.
They have some image in their mind of how “Evil” will be really cool, probably edgy, and fun… for them. What they aren’t usually thinking about is how “Evil” could possibly wreak havoc when put in a pool with the other characters in the party and told to swim as a team.
No player wants to get stabbed in the back by a fellow player, because it was in their “Evil” nature to do so. No one really wants to RP their character’s rape or torture, either, for that matter. Heck, even just confronting another player over an in-game stolen wallet might be more than some players want to deal with!
It takes a lot of trust to get a good game rolling, and nothing breaks down that trust faster than “Evil” characters who the other players can’t trust in or out of character.
The hardest part about playing an evil character well is that you actually need to start by being the most unselfish person at the table. You need to be willing to find out the boundaries of the game and the players from everyone playing with you, know what lines not to cross, and do a lot of “yes, and…” from improvisation games to keep your player a part of their action, instead of treating them like they’re all part of your story.
I don’t blame any DM for banning… or at least having a VERY STRONG SAY… when it comes to evil characters.
Evil campaigns can be fun; one-shots of thieves, murderers, or mad wizards can be a riot, but there needs to be a lot of trust between the players and the DM to pull it off.
It’s hard to generate that with evil characters due to the nature of evil. And it’s even harder when someone is trying to be “Evil”, the glorified version of evil that they have in their heads that might conflict in major ways with everyone else.
In the end, it’s up to the DM and players on how to do evil PC’s. With smart decisions, good communication, and most importantly, BOUNDARIES, it can be really awesome. But it’s a headache you have to plan for, and some DM’s don’t want to go through the extra legwork.
Personally… I play Paladins, and I’ve seen the same argument against Paladins over being “Lawful Stupid”. I get it. I’d still rather see Paladins at the table, but that’s because there’s a difference between outlawing a CLASS from the table and an ALIGNMENT. But that’s an answer for another day.