Evil is played out. It's kind of childish.
To do something bad for a good reason is better.
Look at Saren, he THOUGHT he was doing good. Maybe we will have companions that just want to establish a new colony and is willing to wipe out the native species so their own species can thrive.
I'm gonna pull the evil is relative here. These evil actions may not be evil but just human motivations and feelings like fear and selfishness or personality like being aggressive and jerky to NPC, stealing from them or it could be actions that may be more on the practical side like sabotage the Krogan's cure because they may think Krogan is a dangerous and aggressive race that can reproduce at an alarming rate. FemShep from Fallout 4 is kinda like that, she likes stealing and like selfish actions, demanding more money. It's more about player's agenda and have your character not being judged or annoyed by your companions by allowing us the have people who may be in favor of our actions, especially when companions are always an important element of Bioware games. It's not about having evil for the sake of evil but being around people you bring around the game that you have something in common with. I like to surround myself with likeminded people, and if I choose to play good, I could bring good people, and if I want to be a jerk, I want to bring jerks with me. Otherwise, it's not really it's just more of the developer's agency instead of player's agency.