Generally speaking, the truly evil people of the world prolly don't plunk their arses down in front of te computer to unwind with a little rpg action or so. If that generalization is correct that puts the majority of the rpg buying populace on the side of the "good guys". Sure we can all take a moment to fleece a store of the goods [how many threads on here pertain to "theft" as a means of improving the character through then selling the purloined goods back to the shop owners themselves, lol try that in Morrowind] but in the process of playing the games we find ourselves on the good side of the law and again in most if not all instances the underdog from beginning to end. If evil were to win then it would be a bit demoralizing to say the least.
Basically I presume the truly evil to be out doing evil rather then racking up orc kills. Thus it's marketing to the target audience in a simplified way of thinking.
