I think that we (the forum we) tend to look on Alien3 much more kindly because I would guess that most of us have seen the superior Assembly Cut.
Alien3 was really poorly received - Fincher has disowned it: even he hated the film (studio interference, getting told what to do, etc). But ultimately, the theatrical cut was - by and large - regarded as a bag of shit. Even if it made money (as we said before - have someone pissing against a wall and put "Alien" in the title and you've just made 30 million).
From the drawings, it's pretty clear that Blomkamp was going to retcon the franchise.
It's a strange one though - we discussed the "happy ending" earlier: does a happy ending work for Alien(s). Well, by and large (in my view, but that's purely subjective), but my thought is that ultimately, Ripley and Hick's fate may well be sealed (if the suicide bomb vest is anything to go by). So almost certainly Ripley and probably Hicks are marked to to die. If that's the case (and it may well not be, I'm just postulating based on the drawings), then why bother with a retcon at all?
I think simply because the way that the two characters were hand-waved out of Alien3 (to serve the plot) was pretty poorly handled. We get that the point of the film was to have the Alien take everything away - understood. However, it was a bad way of handling it after the success of Aliens - it just wasn't the way to go.
It's a bit like the next Superman film opening with him standing at Lois Lane's grave and Perry White saying "That plane crash was just awful." Yes, it opens the door for a Superman / Wonder Woman romance if that's what they wanted to do, but I'm not convinced that anyone would be satisfied by that - even if it served the plot. I'm just making that up to illustrate a point, by the way.
I can't honestly believe that anyone who went into the cinema having seen Alien3 came out thinking "that was the film I really wanted to see." Whatever its merits and flaws, it was not what the franchise needed at that time. I was so hyped for it (we saw Aliens every week in the Curzon - we were so regular they gave us all the merch when the run finally ended - standees, 10x8s, everything) and I came away reeling not quite sure what I'd seen. Only that I was underwhelmed.
The issue comes with "Ripley's Nightmare" or just ignoring the events of the last two movies (a la Superman Returns). "Ripely's Nightmare" isn't as daft as all that after what we saw in Prometheus... dreams are a big part of Hypersleep it would seem. All it would take would be scientists standing over the cryotube with grainy images of the past two movies flashing on the screen as in the dream sequence in Ridders movie. We think its silly - but, given what happened in Prometheus, "Ripley's Nightmare" is actually keeping with the "science" of the movies.
Clearly, these drawings were done before all that - but now it actually works better as an explanation than having to serve it up and justify it in a retcon - as the device has been used before.
It's frustrating - I guess we'll never know what he intended to do - what the retcon method would be. I just don't think the events of A3 and A:R could be ignored like Superman III and IV - they'd have to do something with it. But "what?" remains the unanswered question.