It gives people within those cultures an ability to access information they're not supposed to be able to, while also helping protect them from those in power.
Yes - I think it'd be great if American companies didn't build the censorship or surveillance infrastructure for these countries and I think it's wrong that American companies enable these governments to do this to their own people, but at least through Tor we can side step the cultural imperialism argument.
Only those who want it will seek it out.
Edit: If you're interested in running a non-exit relay, check out this guide I made - it's pretty easy to do (plus you get a cool shirt after 60 days).
https://tor.stackexchange.com/questions/6567/how-do-i-manual...