Personally I think "cool" is so subjective and vague it's hard to know how to answer.
For example WHY are tube sites cool to you? Convenience? Variety? Accessibility? That could help guide the thought experiment.
Though for me, the thing SLR could do to improve desirability(again, I don't know about cool) is variety and production design.
What tube sites have is access to lots and lots of videos where the amateur content often looks as good as the pro stuff(these days at least). VR just doesn't have that right now. Yes, more smaller studios are getting into it but a lot of them struggle with image quality and camera positions. They don't seem to look at what works at the bigger studios. Reality is we want get a fun inventory of niches like the tube sites have until more smaller studios exist and can produce decent quality. SLR could probably reach out to these producers and offer their knowledge or sponsor in some way creative amateur producers until they're on their feet.
Secondly, when I say production design, what I really mean is being more specific in the choices of a scene.
My go-to example of almost being something is the recent Chanel Camryn/Leanna Lovings SLR scene. Chanel makes an accent choice during the speaking parts that was great but then she immediately dropped it during the sex. It was disappointing.
Things like character choices and costuming and location and positions all working together to benefit a specific script. A common issue in vr scenes across studios is that as soon as the action starts, the premise is pretty much out the window. There's no character or storyline anymore. No dialogue that continues the viewers immersion. And what might be there is the bare minimum.
Admittedly it's risky. When a performer is cast in porn, people just want to see them do what they always do, look how they always look, sound how they always sound and anything that breaks away from that is "bad."
But all I can say is personally, I'll accept there's a risk that a director/producer might make bold choices I don't like if there's a chance one time i REALLY like them. You won't make everyone happy but playing it safe where you might have 10 hypothetical Blake Blossom scenes that are all pretty well shot but also all pretty much the same doesn't help things evolve. Because I'll ultimate just keep going back to one or two of those every time and ignoring the rest.
Instead if I have better choices like "oh, in this one she's a reserved cowgirl ready to lose her inhibitions." Or "in this one she's a hard-nosed detective." then I have cool choices.