Is this largely due to most of the NPCs there being quest related?
I can completely see why stuff wasn't locked, houses open up as you go along the questline and I have always liked to go in the houses and talk to all the NPCs for example.
But I do think there are a number of non-essential/non-quest NPCs who could be flagged up for pickpocketing (there are loads of "Coldharbour Survivor" NPCs if nothing else). Also there are a couple of houses that I have noticed are never accessible, and a couple filled with non-quest NPCs that could be given the justice system treatment.