Bladerunner isn't that great .. well, it's alright. But it set the aesthetic. In the same way that the book Lord of The Rings collated and set the aesthetic for lots of similar tales and settings. And how things like The Matrix set the aesthetic for many similar movies.
The problem - The Matrix was good because it wasn't trying to be too clever, it just introduced you to a well-thought-out universe with a unique aesthetic, You can drop in the deja-vu, and the "bound by rules" and all the other bits and it's all new, fresh, interesting and makes sense. The rest of The Matrix movies are trash. Literally just action films where he gets more and more ridiculously powerful. Boring. (God, just remember that final fight between Neo and Smith that just goes on forever while they destroy the world around them... you just think "You might as well just give up, because beating each other with lampposts etc. isn't working no matter how many times you do it"). I would hold that the thing that kills the Matrix sequels is, quite sadly, the whole human city thing. Too much time in caves and pipes and not enough inside the Matrix, and the time inside the Matrix is just never-ending fighting with someone who basically doesn't really get hurt.
The same happened with Alien / Aliens (both set their own kinds of aesthetic, I happen to think Aliens is much better in doing this). Everything past that was just "let's throw in something different at random" while pretending it was more of the same. It wasn't necessary, it didn't really work, and now the whole franchise is just trash. Alien 3 figuratively changes the colour of everything (and literally, too - think of Aliens, you think blacks and blues, think of Alien 3 and everything is brown, even the alien), even though the story has gone "unskilled crew vs alien in confined space ending with lone woman, over-equipped military against alien on huge planet, unskilled crew vs alien in confined space).
There are lots of movies that set their own aesthetic, most are not all that good. The early Star Wars movies, moves like The Thing (for zombie/alien like movies), etc. If you are setting the aesthetic for a genre that's not been seen before, it will become yours, and that movie will be used as the standard (I've heard many people see/read cyberpunk stuff and call it "Bladerunner-esque".
But the problem is that new storylines and new aesthetics are few and far between, and aesthetics are easily ruined. Those kinds of opportunities can be squandered. And sequels don't work too well once you've set the aesthetic as you're then competing against a movie with the same name and idea and aesthetic. Alien/Aliens is probably the only one I can think of that's really successful in that regard, almost because it's two different movies: "alien vs lone survivor" and "alien vs elite military unit packing state-of-the-art hardware".
It's not even about original actors, or same scriptwriters, or same directors, etc. Remember Highlander? First was great. Second was trash. The aesthetic change kills it.
Bladerunner set the aesthetic, but then was also overrun with re-interpretations. Sure, everyone probably likes a different one but it hit saturation really quickly. That's cost it dear in the sequel-viability stakes, as has the amount of time that has passed. Again, going back to Aliens, it had the Special Edition - people will prefer one or the other. [Special Edition is better than the original (if you exclude all the namby-pamby Ripley-famliy nonsense)]. It was a way to get "more" out of the original Aliens aesthetic.
But sequels don't cut it. They change too much, alter the aesthetic. The movie that makes a second aesthetic that's as good as the first, without just piggybacking or reinventing everything, is really rare. I foreesee any Bladerunner sequel trapped there - they can't abandon the aesthetic of Bladerunner, but they also can't add much to the story that will introduce new things to it without breaking into something else.
And because it's an undefineable quantity, it's almost impossible to promise or to prove, so any such attempt to follow it with even the smallest claim to being able to replicate (ha!) it is really quite dishonest. When film people say "We're going to move in a different direction", it's because they know they can't compete on an aesthetic level.
I think what Hollywood misses is that often we want more of the same, without having to put in "new" stuff too. We'd give our hind teeth to make the Aliens movie just 10 minutes longer, but we wouldn't want fleets of marines arriving to take out the mega-queen or whatever. I'd love to have had The Matrix play out to a movie twice as long with some of the elements of the later movies, but as soon as you shut the clapperboard for the last time and then try to resurrect it a year later, you lose it.
Aliens was so cool to me, that when the Colonial Marines video game came out, and it had original voice, sound effects, licence, etc. I was over the LV426. Now I could play IN THE MOVIE, as it happened, with the same aesthetic. But, no, it was just dire because it was all reinterpreted, and rushed. But I was more hyped about being able to BE Hicks, exactly as it was, exactly like an 80's movie, with motion trackers that now look out of the Ark, and original gun sounds, etc. than I was about any of the movies that followed.
You have to keep the aesthetic. Nowadays. I imagine any sequel would be destroyed by over-use of fancy special effects, rather than just keeping on par and inventing new twists rather than just "telling us more" about the story.