I share the same concerns, though it's clear from the live stream that not everyone is on board with the karma system yet and Larian is still figuring out if/how they're going to do it. I think a good question for Larian to ask themselves would be "has anyone ever done a karma system well in a video game?". Judging by the games I've played, the answer is no. So unless they've got some brilliant idea that the rest of the industry hasn't thought of, I'd be very hesitant of this feature.
I also think Larian should ask themselves "is it even worth it to try and do this? What are the benefits?". Because for me, it's a pretty hard question to answer positively. Yes, you can reward the players for the choices they can make but... This is a roleplaying game, aren't those story driven choices the reason we're playing in the first place? The choices we make are going to lead to cool encounters, fun fights and epic loots. That's reward enough for me. On the other hand, the potential negatives of screwing up a karma system are quite high.
