Anakin had the same clothes in Episode II. He just happened to pick a dark look, which was fitting. You couldn't have someone dressed like Obi-Wan or Yoda going to the dark side. In fact, of the Jedi with speaking roles, it seems that the shading of their clothes has a lot to show about how they conduct themselves. Yoda and Obi-Wan's clothes were very light, Mace's had a darker tone, as did... whatever the name of the Conehead Jedi Master was. I won't even try to spell the name because I'll mangle it. Mace and the Conehead spoke of taking control of the Senate and overthrowing Palpatine, Yoda and Obi-Wan spoke of moderation, and of course Anakin ended up plain evil by the end.
Han Solo met Chewbacca when Chewie was a slave to some Imperial officer during Han's time at the Academy. I believe Chewie was being abused or something, and Han saved him. They then fled and became nondescript smugglers, and Chewbacca owed Han a life debt for rescuing him so he hung around to protect and help him. There were rumors of a scene where a young Han helped save Yoda from the clone troopers, but it was thankfully cut, as was another rumored Yoda farting moment.
What pisses me off is that Luke's attire in ROTJ prompted Lucas to say "now that's what a Jedi looks like," but he decided that they'd all end up wearing Obi-Wan's desert hermit clothes. I guess you can't be virtuous and all that in a badass black outfit. Makes sense, but I'm really not a fan of the super impoverished look. Anakin and Mace's costumes (moreso Mace's) were a nice compromise between cool and humble.