A reason why the Aliens are so weak

[Purebreedalien]

Babies being facehugged... that will disturb me greatly seeing their little chests burst as thy cry their tiny eyes out. I can kind of imagine that. Little babies sitting there as some scary alien smashes through their rib cage. I feel sorry for them and i dont even know that if it is going to happen. I don't really like films where babies get hurt it makes me feel all depressed for some weird reason. 

[Johnny Handsome]

Could be a reason why they're short too. Well thats my reason and I'm sticking to it!

Or the reason is just that they are like always, but the predator is stronger this time.
Thats what im sticking to.

[marrerom]

Could be a reason why they're short too. Well thats my reason and I'm sticking to it!

they might not be shorter.... its impossible to tell with out seeing the movie but the scene in the trailer where wolf is grabbing 2 aliens at once they are as tall as he is. so for that scene at least they will be normal height.