So the question i pose to you is clearly : Why the Alien has not return in more dramatic grotesque forms
'The answer is simple' : Censorship or being X-Rated
Now people wonder why Ridley hasn't exploited a new genre of Alien/human horror is the fact that there is one thing that is generally understood and that film makers CAN NOT DO: Defamation of the human form that crosses the border of what is tasteful and what is profoundly a desecration of the human form for the purposes of entertainment.
For instance: To place a Penis is front the viewer is completely outrageous. IT AUTOMATICALLY changes the rating to NC-17.Or X-rated.
Not that the alien is a penis, but the idea is not just a penis. There are things like heads exploding, defaming the human form with abstractions that are deemed too sick or disturbing for adult viewers. Then you change the association of the film to something that is more along the lines of SNUFF films. So unless things like this change in the industry, I don't believe Alien films will ever see the light of day. We will get however, half baked Aliens in more intelligent stories that contemplate existence and GOd..ect ect ect ect ect.......
Consider this, The Last of Us is SORT of surpassing censorship but it still has some way to go as it were JUST A GAME. You are not going to find a zombie film that exploits a face becoming some deformed mash for the entire film, but it would appear in shoddy 3 second poorly created practical effect.
HR GIGer is a prime example as his works depict things inwhich we would NEVER see in film unless certain censorships would move aside for it to be done. For example, photorealistic babies diseased and in weird molds and such.
Something like that on film would disturb the crap out of people and would probably be censored out to get a PG rating.
So my point is not to be entirely angry at this reason but its just to hold a light to the legal ramifications of why we haven't gotten a truely HORRORIFIC Alien film lately. Prometheus did do a good job at keeping things fresh and nodding to Gigers legacy of work. I just would like there to be more of that. Otherwise, there is going be a mess of shoddy Alien Covenant sequels.