The reason Alien 3 failed - at lease for me, has everything to do with studio politics, i.e. $, and nothing to do with creativity. Both Alien and Aliens in a sense are director-driven vehicles - one man, one vision, little studio interference. Of course Alien 3 was well directed, I think the film's rarely criticized for lacking style. But what the studio did to Fincher was almost criminal - I mean, they had a release date and no script - good times!
If Aliens had failed as a sequel, the series never would have become a franchise. Again, for me, Aliens opened up and expanded on this fantastic, working, functional, world created by Scott, O'Bannon, Shusset, and the others - hell, the ENDING of Aliens left audiences with one of the greatest cinematic lay-ups of all time. I mean talk about squandered opportunity for both the fans and the studio, can you imagine how much money the movie would have made if it had been embraced by mainstream audiences like the previous two?
I would have LOVED to have seen a film where the Sulaco returned to Earth - and the "logical" continuation of that storyline (with now both the military and the company invested in "what next?"). Some of the potential scripts touched on this, but of course we ended up with a patchwork of ideas from various drafts and several different writers. The first movie was about a small group against a single alien, the second, a slightly bigger group against 157 of 'em, and in the third, we went back to a single alien, and ultimately backwards, at least to me, into territory already covered in the first film.
(oh, and the facehugger sound effect in the home video release was added in YEARS later AFTER Alien 3 had been made.)