I think it’s merely a design preference. But I preferred the used universe of Star Wars 1977 over the bright and clean cgi esthetic of the prequels. It lent a sense of authenticity and realism that the prequels lacked. And that also the sequel trilogy lacked.
I’d suggest it’s also a totally different part of the galaxy mostly, at a different time. Why would it be the same if the place, time and structure of things is different?
The dinged up and dirty and dingy look of things. Landspeeders, the Millennium Falcon. X-Wings of the rebel alliance. Lightsaber hilts etc, blasters. Kenobi’s Robes. The detail work on Threepio and Artoo. And on Vader’s suit and all its parts and pieces including the cape.
Being older things, I think makes sense they’d be that way. New things owned by politicians and newer Jedi with more resources, I think it works that it’s not that really.
And how the Rebels were much more utilitarian. the Empire more clean and antiseptic and austere in design. How the rebels could just be farmers or privateers or whatever port of call they hailed from. Some of them might even be criminals like Han Solo. Or people out on the fringe. Luke being a former moisture farmer and all of that. Kenobi being able to pass as a Tatooine local wearing the garb of a farmer. Of course, they made those Jedi Robes.
Who said it was the garb of a farmer? There’s similarities I think (robe and neck thing mainly), but Obi-Wan’s clothes aren’t what I see as aggressively similar. Obi even has a clasp on his belt for his saber. Also, ROTJ is the movie that showed Anakin wearing the exact same clothes as Obi I think, in his post Vader form.
I think each world and culture should have varied more in the prequels. You would only get bright and Shiny on Coruscant but not on the lower levels.
I think there’s more of grungy kinda vibe in the lower levels when we see it in AOTC. And the Gungan city I think looks neither like Coruscant or Naboo. Similar with Geonosis and Utapau not looking like any of them.