AVP didn't have the gore of the other films, on top of this, Paul Anderson doesn't know the first thing about preds, the reason why they skin & hang up their prey is to intimidate the rest of their potential game, & to let rival hunters know not to muscle in on their hunting grounds, there was no point for this at the time however because Scar, Celtic & Chopper were all working together on a blooding hunt, so there was no need to ward off other hunters, & they killed off all of the humans that fast that it didn't really matter, they weren't their intended prey in the first place so it doesn't make alot of sense, just shows Anderson's lack of knowledge from the pred's POV.
AVP is full of plot holes anyway, little things that aren't done right, things that should have been different, etc. But I think the main reason is that AVP was intended as a PG-13 movie, eventhough ppl younger than 13 are watching movies much more gory than the alien or predator movies nowadays. Btw, welcome to the board m8, hope u like it here, if u have any questions, feel free to ask