As long as that plastic is REALLY strong, then I think those are actually a good idea for a lot of people. I don't think it's intended for repeatedly slamming it into rocks and mounting a winch in it. But if people just want a stronger bumper than stock and don't want the added weight of metal, I think it's a smart idea. It's just not for serious use off-road.

I've previously read an argument about the pedestrian injury issue with bull bars - I think it's partly because the upper bars will cause broken bones instead of the person rolling onto the hood. And it might be a little more likely that a pedestrian will go underneath instead of over, once they've been hit. I don't see much difference with a plastic versus metal bumper, unless it'll deform a long ways in an impact - in which case I'd say it might be worse for hitting a deer and the bar will angle back and launch the deer upward and into the windshield. Of course, this is all just guesses.