I sure hope so, it would be nice to have some actual variety when stumbling across some raiders. In Fo3 they did pretty much what you stated, although in the subway tunnels they did hide behind columns from time to time.
Maybe the AI should act differently depending on what difficulty you're playing on...?
I think a better idea would be to base the AI off of the enemies Intelligence stat and what faction they're in, not the difficulty level. Most raiders are probably a bit below average in intelligence, and don't get military training, so they should take SOME cover, but not react well to flanking or anything like that. NCR troops, on the other hand, have more training, so they get into cover faster, react to enemies trying to flank them better, communicate enemy locations better, etc.