Imo most developers either don't have the balls or the creative insight to pull off a legitimate Blade Runner game. Some are probably just busy with other creative ideas altogether.
Those that love the Blader Runner stories and that sort of world-building know when something is successfully in the vein of Blade Runner and when it's not; with the recently revealed Black Lotus series serving as a prime example of not understanding your source material.
To extrapolate on your point, it's not just about getting the aesthetic down, but also understanding the tone and themes being explored in Blade Runner stories are also crucial.
The world has to be a primary focus, characters need to respect the logic and rules of the Blade Runner timeline. I'd expect a detail-oriented open world, with respect to AI behaviors and map design.
The map design can't just be a generic cyberpunk megacity. It would have to be a thoughtful interpretation of future Los Angles within the Blade Runner timeline.
Especially if it's going to be open-world. It can't just be a vast map to pilot a spinner from point A to B, as fun as that might be. There need to be worthwhile interesting motivations to pilot your spinner to a certain destination, and I'm not talking about another NPC fetch quest or fighting some enemy either. I think that characters in this world would have to be very well realized in order to be effective.
An open-world in what I would consider a legit Blade Runner would have to be Rockstar's quality of open-world design and attention to detail. RDR2 made me realize how extremely good Rockstar is with thematic settings. The immersion was insane, even despite some of what I would consider as flaws. I need to be able to get truly lost in that Blade Runner world.
I am curious, who would be your ideal developer(s) to pull off an open-world Blade Runner game?