Because, at least to me, those Robocop isn't a franchise that I, personally, hold in high regard. Don't get me wrong, whilst I've only seen the remake, I do love Verhoeven but I just don't consider those series' as important as Alien.
And that's your opinion and that is fine. I will even agree that Alien has contributed more to film as a whole than Robocop itself. I personally hold Robocop in high regard but that's mostly for nostalgic reasons but as far as contributing to science-fiction and film as a whole, then those accolades would have to go to Alien.
You are entirely correct in that the film doesn't need to address alternate timelines or realities but they're very existence implies the use. And that drags it out of realism for me, by the mere implication.
And this is would be one of those rare times where we agree on something. This could even apply to Predator and AvP. The movie doesn't have to address alternate timelines or realities. A lot of franchises, especially science-fiction franchises do this. Robocop having being among one of them. Other franchises which happen to do this are of course, Highlander, Halloween and most infamously Godzilla. Now.. on screen, in dialogue, and script wise-- as far as I know none of these franchises have addressed openly that there are alternate timelines or even parallel universes. The only exception being the Heisei Godzilla series since Godzilla vs King Ghidorah did involve time travel which retconned Godzilla, Godzilla 1985 and Godzilla vs Biollante out of the Heisei continuity.
But even if a franchise's continuity doesn't address alternate timelines or realities, I don't see how their very existence implies anything that would affect storyline of a particular continuity. It's not like that continuities would be crossing over, that would require a plot device such as cosmic interference or dimensional barriers breaking down requiring the use of a device.
Again, going back to Robocop.. when I watch the source material, the movies.. I don't think of the Marvel-Sunbow, TV Live-Action, Alpha Commando or Robocop comics when I watch the movies. They have no bearing on the continuity or storyline of the movies. Doesn't ruin the realism for me.
And it wouldn't most certainly ruin the realism for Alien, Predator or AvP.
I know you'll not agree with any of that because of your own preference for your multiverse. But that's where I'm coming from. And like I said, if Alien 3-2 is awesome then I'll be a happy bunny. But a part of me will always be a bit peeved.
All I want to do is merely challenge the way the fandom thinks. Sometimes even challenge those in the fandom who have a voice. Most people believe it has to be black or white. I'm saying.. it doesn't have to be.
I've seen fans argue that there are things which are canon or not, and then there is the debate over Blomkamp's word. I've seen this happen similarly with Rodriguez's and Antal's word on PREDATORS. But in the case of Blomkamp, everyone is still confused if this is a retcon or a continuation. Everyone is divided, and that's fine but I see a middle ground. And I want others to also see this middle ground, because assuming what Blomkamp is saying about not undoing Alien 3 and Resurrection is true and what I assume it to be, then that middle ground leads to a path where there is a compromise. An alternative.
I mean.. I understand about being a bit angry. I'm myself am still a little angry about the retconning going through the franchises, especially with Predator. But if Blomkamp's word about not writing out but ignoring Alien 3 and Resurrection, but tying into Prometheus is worth it's weight in any capacity... and if it even indirectly means we have an alternative.. I'm going to take that alternative and be happy with that alternative.
Would you accept a canon that just makes you angry because of changes you don't agree with? Or take an alternative which allows for stories and concepts to legitimately exist in an alternate of sorts and not just personal canon?