Larian has confirmed that for now they wanted to put out the more evil type companions. They said that normally people want to play the Good guys, and in most games that is the only route to satisfactory results or interesting gameplay. But in BG3 they wanted to allow more different playstyles and hence the first characters you see in EA will more likely lead you to those different playstyles to see that "hey, this works as well". Good guy companions will be coming to the game at some point.
This info is from the twitch.tv chat with Swen. Link is in his twitter.
