If you find a group that lets you play evil go for it. My friends never played evil and I would have said no if someone asked. And, as I assume you know from the way you formulated your response, most DMs say no because evil party members usually spoil the fun for others.
If we look at the successful games of the genre most have had a heroic narrative. There's a reason Larian asked us to test out the evil path - because they know that very few players do so of their own choice. It's just not much fun to play - the joy of slaughtering a group of refugees so you can sleep with an evil priest is lost on me. Attempts to make game that favor evil just don't sell. Apparently lovers of evil playthroughs think that Tyranny is one of the best RPGs ever made - but the number of people interested in playing it is very very small . . . I'm told that Monte Cook is the best RPG designer ever but, strangely, people don't like to play his games . . . But, again, I'm not here to stop you.
But have said that I don't want to see the setting degraded. I don't want to see is Faerun transformed into Greyhawk 2.0 or for tons of resources to be wasted on paths that very few people are going to play.
Because, again, evil isn't much fun and I just don't see evil as an advanced or more intelligent playstyle, if anything it just seems like real world morality brought into a video game. [ I had lots more typed here but I decided my tone was too strong - please know that I disagree in the strongest possible terms
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Now WOTR seems to be an exception - I'm happy with the game and, apparently, people like playing a lich who leads an army of the undead. Somehow WOTR managed to support 3 evil paths in a way that a) didn't reduce the amount of playable hours available for the good paths b) sectioned off the evil path from the others and c) didn't make the plot into a forgettable mush like "you're just a mercenary trying to make it through life" or "the only thing on your mind is surviving the day"
