TheoOdo said:
We may agree that it's silly for Obi-Wan to be dressed as a Jedi whilst in hiding, but it's been established - from Return of the Jedi on, if not earlier - that that's just what he was doing.
This is compelling evidence. But what about:
Is it because this is truly the outfit of peasants and Jedis have adopted it? It is a little odd that no distinction was made between Jedi clothing and Tatooine clothing.