Its obvious being that being "good" has received the bulk of the development. With voiced characters, storylines, games, songs and etc.
Being "evil" is just a gimick to fight NPC's you would have otherwise interacted with.
Just think about it this way. Where is the Alfira of the goblin path? Volo? Whether I am good or not I can always get him but the only way to interact with Alfira is help the Tieflings.
I guess you could argue that I could join the Tieflings and see all these things only to betray and kill them. I mean Alfira says she is going to this famous Bard's Inn in Baldur's Gate. But if I kill her then her storyline is over...
If I was evil I wouldn't murder her for the lolz. I would just enslave her and have her sing for me for free... seems more practical to do that imo.