My only commentary on Luke's wardrobe in ROTJ... Watch "From Star Wars to Jedi" (and fast forward up to the ROTJ stuff). Lucas and Mark during the costume test sessions. Mark observes it fits a lot like his in the original film. Lucas responds, saying yes it's a lot like the original, but the black makes it more Jedi-like. Many non-violent, even pacifistic monastic orders in history have used black habits.
I only wish they'd kept that dark gray sleeveless kimono long, rather than cut it short to facilitate his stunt-work. From fencing in high school, lemme tell ya -- if you can't fight in flowing clothing, get a new teacher.
That's also what the early concept art for Phantom Menace showed for a younger (and solitary -- it was before Qui-Gon was added to the story) Obi-Wan. Black tunic and trousers, gray sleeveless robe. That's what I'm doing for my Jedi outfit. I reject the "George's bad memory" revision that the Jedi uniform is Tatooine homesteader garb.