I never got it either
Until my dad and I were marathoning the series. He had only ever seen the first one, and he had an absolute blast rewatching, both of us were utterly in awe when we saw it.
He was genuinely surprised when I said there was a second and third installment ( conviently forgot AVPs and the then upcoming The Predator )
and he hated the second one so much. And he did not even expect Arnie to return at all..
He said it was way too over the top, cheesy and did not feel like the characters were actually people.. just real life cartoons.
He did like the last act though inside the predator spaceship.
In contrast he liked Predators very, very much.. neither of us were truly enthralled, but he considered it a massive improvement on the cheese-fest that was part 2