Hmmm, *thinks of examples* Morrowind had random, though there is a mod (not sure if I downloaded it though) that had merchants walking back and forth between major towns. W+W: Joan of Arc, they had random walking around people, who DID NOT FLEE THE ENGLISH WHEN THEY BREACHED THE GATES. Though Enlight had some AI problems (among their bosses as well) in that game.
Yes, people with putpose is nice, or atleast even having 3 or 4 or more little tasks to do even without walking, (eg, sitting at table, drinking, chatting, etc).