I fell like the current trilogy was criticized so much, at least by fans, because it neutered the xenomorphs, and to an extent, the travelers.
The original Alien was a Haunted House movie, tried and true (only in space)...with a monster from the shadows that no one really knew about. It was hard to pin down, had zero origin, other than a wierd space ship with weirder pilot and was all the more scary for it. Aliens was a hardcore action movie about humans getting even with this evil darkness. Aliens3...Well, that suffered from the 90's wanting its' own Aliens....
But..the point is that the Xenomorphs were an unexplainable evil.
The new trilogy shows them to be a handcrafted weapon of a flawed human creation, designed to the embodiment of man's destruction of self. Xenomorphs kill 'the creators' (man's destruction of God), Xenomorphs were created in a manner similar to the development of medicine through history (man's atrocities against man -See WWII), Weyland desire to live forever, to control mortality, ends in his death (the inevitability of death), etc. even the future connection to The Ripley Alien movies drips of 'if you forget the evils of the past, you are doomed to repeat them.'
Basically, Alien went from a fun Horror Flick to extistentialism in Space. Is this, necessarily a bad thing? No, not exactly, but it did lose it's way, and its' 'identity.' Then again, one could argue that Resurrection was a warning against Humans messing with nature and a direct warning against genetic cloning, but that movie was...an attempt to return to the Aliens mentality and find a way to 'shoehorn' Ripley back into pop culture consciousness.
But take that with a grain of movie popcorn salt. I've only had six hours of sleep, combined over the last few days.