Originally Posted by El Argentino
What is this?
Originally the robes were not meant to be a Jedi's outfit. In fact the reason Obi-Wan was wearing robes in ANH was to blend in to the natives and be inconspicuous. He was in hiding. It never really made sense for him to have been wearing a Jedi's uniform in public like that.
My understanding is the form fitting outfit Luke wore when confronting Vader in ROTJ was much closer to the original design for the Jedi. There are comics that came out before ROTJ that actually depict Jedi is such outfits.
That all changed when Lucas decided to go with the robes. Thus why the force ghost Anakin at the end and prequels showed them in the robes. It's just one of many changes Lucas made to the movies while in development of the OT.