I'm pretty sure it was just originally just Tatooine gear or perhaps later "Jedi in hiding" gear, considering Yoda's attire too. Regardless, I don't think it was initially meant to be the standard apparel of the Jedi in their prime. I seem to recall during preproduction of the prequels, there was a lot of discussion and concept art exploring what Jedi wore, and I think some even depicted armor, similar to what we saw in TCW (and yet strangely never see in the movies). George ultimately went with the old robes, which makes it seem rather silly that Obi-wan is hiding yet openly wearing Jedi sashes and robes.
I always liked this scene just because it does seem a little mysterious and ambiguous and as far as I know it's never been explained. I think I did read speculation once that all the gas and vapors seen in the freezing chamber might be very flammable and a blaster shot would've blown them all up. Haha!
I remember when it was announced that Chewie would appear in ROTS, there was a lot of speculation that he and Anakin might share some scenes together and the ESB scene would be a reference to Vader not wanting to see his old friend hurt. lol!