Maybe Predators are not technically biological predators, but the biological definition isn't the only use of the word (e.g. sexual predators). Using the word "Predator" instead of "Hunter" suggests that Predators derive something essential from their activities-- it's not a sport for them, it's a way of life.
This article also gives too much credit to simplistic evolutionary-biological explanations of modern cultures. Assuming that Predators were shaped by evolutionary pressures like ours, then concluding that they are "failing as a species" because they are "acting against Darwinian pressures", is intellectually lazy.
This whole thing reminds me of the kind of pseduo-intellectual justifications historically given for slavery. They are part of a "backward" culture in some ill-defined way.
Whew, maybe this is an over-serious reply to this article, but I prefer to practice critical thinking when I can, especially when it comes to portraying other cultures or species (fictional or non) as backward.
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.
I don't know how seriously I can take this kind of speculation, though. Unfortunately, we only have one data point to work with when it comes to technologically advanced species.
For more on how different other intelligences could be from us, here's some entertaining sci-fi: http://lesswrong.com/lw/y4/three_worlds_collide_08/ Previous posting: http://news.ycombinator.com/item?id=1387771
I've always thought of the Predator series as being based off The Most Dangerous Game: i.e., these guys had become such ruthless and efficient killers that going after their normal prey just wasn't fun anymore, and they had to get their kicks by hunting sapients like us.
