Like any monster movie, they have to include a bunch of human characters in order to establish the idea that a monster is around and ready to attack. At least Predator had a strong ensemble cast and you could empathize with the humans. (Well, sort of.) And you can see plenty of clues that the Predator is sneaking around, learning about the humans and getting ready to pick them off one by one.
Actually, the last time I watched the original Predator, I found myself empathizing with the Predator more than with the humans. Go figure.
I also just watched Aliens vs. Predator: Requiem for the first time over the weekend. They must have saved money by not hiring a lighting director or a lighting crew, because almost every scene was shot in the dead of night with the lights off. And AVPR's human characters were definitely made of cardboard, and it was hard to care very much about them.
If nothing else, watch the original Predator to hear the famous line, "Run! Go! Get to da choppah!"