For me real universe shrinkage isn’t constantly visiting and finding out more about the same place. It’s hopping around places with different names that look the same and not finding out much about them or their cultures or customs. If you were to merge all that sand into one pile you would have one interesting and well explored place. Instead of three almost identikit places where only one is really explored.
To be clear - I definitely wasn’t advocating a Jakku type situation, where the planet’s aesthetic remains the same and only the name is changed. I’m really very ignorant about the technicality of such, but what I was proposing was a radical redesign of Tatooine in ROTJ - such that the exterior shots are unrecognisable, and the planet then becomes wholly new. That portion of the film is largely contained in Jabba’s Palace - save for the droids’ trek to the gate, one establishing shot of the palace, and the barge sequence. So what I would hope for, is a thorough re-imagining of those exteriors. Of course, the barge sequence occurs on “the Dune Sea” - so it will get sandy at some point. But the desert climate in this portion would just add to the ecological variety of whatever the new planet is to be. And I imagine a colour shift for the barge segment, along with new backgrounds, to clearly differentiate this area from Tatooine.
I take your point about depth of exploration, as opposed to breadth. Less can be more - and limiting the planetary lineup might be beneficial if it means that we can better develop the one planet. But I suppose I just don’t buy Jabba’s Palace being on Tatooine; it doesn’t make sense to me in light of ESB’s conclusion. And far from deepening our understanding of Tatooine, I think it actively contradicts the planet as established in ANH. If Jabba is such a powerful figure, who desperately wants Han Solo (and is able to offer an inordinate bounty to guarantee his acquisition), then surely Han wouldn’t dream of trying to drive up business in Jabba’s backyard. Jabba should thoroughly own the muscle on whatever planet he bases himself - so Han should’ve been dead meat as soon as he touched down on the surface in ANH; or at least, as soon as he wandered into Mos Eisley. But nope; only Greedo puts in an effort. And this is because, in ANH, I never imagined Tatooine as the fixed abode of an intergalactic crime lord - rather, I imagined the planet as more of a terminal; thoroughly removed from any power player.
Surely best, then, to situate Jabba’s Palace on a new planet - which would derive its character from the Rancor, the Sarlaac, and all the rest. We don’t spend an incredible amount of time on Bespin or Dagobah - and we only visit the former once, in the whole saga. Yet those locales are undoubtedly rich; so there’s no reason to think that transforming Tatooine into a new planet for ROTJ would necessarily result in a more frivolous setting than either Bespin or Dagobah. It falls to the design elements; and so we’re off on the right track from the get-go, in virtue of the ingenuity on display in this portion of ROTJ. Effort would have to be spent to ensure that the new exteriors are equally as inventive.
And it shouldn’t be overlooked that film is a chiefly visual medium. Each Star Wars film aspires to an epic sweep - from the sandy dunes of Tatooine to the metallic corridors of the Death Star and the lush greenery of Yavin IV; from the snow drifts of Hoth to the swamps of Dagobah and the cloud fields of Bespin. ROTJ appears undeniably bland in comparison. Augmenting Tatooine in ROTJ goes beyond universe expanding, then - it also broadens the film’s palette.