I don't agree with this but this is where the prequels screwed with the Jedi lore.
prior to the prequels, technically the Jedi's didn't have a outfit. Only piece to identify a Jedi was their lightsaber. Or else Luke would had known Obi Wan was a Jedi.
In A New Hope, Obi Wan, uncle Owen and some residents on Mos Eisly wore Jedi style outfits.
RedLetterMEdia/Mr Plinkett mention this in one of their prequel reviews
In ESB, Luke is wearing shirt, jacket, pants, with a blaster and his Lightsaber. And in ROTJ Luke is wearing the black top and black pants.
But when the prequels came out, every Jedi had a robe. So, I don't have problems Luke wearing those robes in TLJ