This is sort of why I was initially rather disappointed with the art direction on KotOR. I think the old 'Tales of the Jedi' comics did a pretty good job of showing a much more primitive looking galaxy than the one we saw in the movies, from the weapons and clothing all the way up to the ships and locations....then in KotOR everything looks very much like the movies. This bothers me since while I can believe that technological development can slow to a crawl, I have a hard time believing that aesthetic tastes, conventions and fashions could become so similarly stagnant.
I agree though, something is badly wrong with the Star Wars galaxy, and that something is that they can't seem to go more than a few centuries at a time without some devastating galaxy-wide conflict. In that sort of environment it's easy to see why advancement is slow and indeed, often subject to backsliding as knowledge is hoarded, lost or even outlawed.