Making things look different from modern Earth didn't require dressing people in such a way as to make them look stupid or pompous. The whole they-should-look-different-so-we'll-make-them-look-stupid thing is just an example of the sort pretention that marks the PT.

There was a variety of clothing in the OT. It wasn't all just practical. Look at Biggs's Tatooine outfit or Lando's Bespin outfit or Leia's ANH or Bespin outfits. The OT managed to give them fancy outfits without making them look stupid. The PT couldn't manage the same because the PT was made with a bullshit atttude.

And you can have different cultures dress differently without going into the sort of pomposity of dress that you get in the prequels. It could even have been made somewhat different from the OT's clothing without being made so bullshit.