Because to me Mos Eisley (the pre-SE version at least) felt much more like a real place. It was quiet and sparse, and there weren't tons of creatures and droids filling every inch of the screen and doing cute gags for the camera all the time.
The same goes for Yavin, and Hoth, and even Endor. They felt like real places you had just dropped in on (and not just because of the lack of CG either).
Alright, that makes sense, although none of these exotic planets ever felt like real places to me.