Now, I think it's interesting to speculate how the Predators might have evolved (unlike the Aliens, whose life cycle appears to be just plain nutty). The two things we do know about them are that they're technologically advanced and have an extreme interest in hunting. They also look like biological predators, with their sharp teeth. So I'm guessing that they're a bit like what would happen if a pure carnivore, rather than an omnivore, had developed brains as big as ours.
I see nothing wrong with the idea that a species could have evolved to enjoy extremely dangerous forms of hunting if that helped with sexual selection. Much like peahens find males who carry around enormous handicapping tails to be attractive, female Predators may be attracted to males who hunt ridiculously dangerous game at great cost to themselves.
I'm not sure about the binocular vision thing: don't Predators have binocular vision? Pictures on wikipedia make it look like they have two eyes.
What I think we can say is that Predators would be crappy predators if it weren't for their technology, but they might have been sufficiently good to get away with it in whatever conditions they evolved in. Crocodiles are pretty crappy predators too, but they seem to get away with their tiny niche quite nicely.