As I said, I never played AVP1 so I did not know how powerful they were, no need for the "What are you talking about?" As I literally don't know how the Aliens were in AVP1, I just tried to use AVP2 as a reference.
But, all you said, just kinda proves my point. If the acid were as powerful as it was in the movie, one drop on the skin and you're f**ked. Game over. One Alien gets behind you, you're f**ked. Game Over. An Alien even gets near you, you're f**ked for multiple reasons. Game over. The only way the movie characters survived was by running, its hard to make a game narrative by running away.
I'm not trying to be a prick here, I'm just trying to say that if developers were to make the Aliens true to what they are, they couldn't make a game out of it.
Now, I will agree with you that the Aliens just jumping down asking to be shot is a bit weak, and that the acid should be more powerful, than nothing at all.
That video pretty much proves my point, too. That one Alien f**ked you. One Alien that didn't come close to the speed or ferociousness of an actual Alien. Now, with ACM, there are dozens of those running around. If they were programed, somehow, as real Xeno's you'd be completely f**ked.