I only saw one Dev comment in this thread, from Josh Sawyer, and he was commenting on rep as opposed to karma; he didn't mention or imply karma at all in his post.

Neutral/Unknown is not a reputation you can maintain in F:NV unless you avoid doing contentious things. There are actually two separate reputation axes for each group/area: Fame and Infamy. If you do things that help the group, you get Fame. If you harm the group, you get Infamy. The relationship of these two scores determines your overall reputation. So if you do a bunch of good and bad things, you aren't unknown; you have a mixed reputation.

This was done specifically to avoid the feeling that your actions "wash out".