I don't see why. Its a ritual, basically survival of the fittest, so why give more of an advantage? The plasma cannons are more than enough if things get hairy, they have nets that somewhat can incapacitate the Aliens and then there is of course the particle bomb.
I guess in the whole scheme of things out in space the Preds wouldn't have acid proof or resistant armour in case Aliens crossed their path either, they're a very proud nomadic hunter race, I doubt they'd even contemplate it.