If all limitations were off the table, I'd put in a working economy. I know that it's unfeasible, but we're talking "if I coulds". I'd have every item in game be made from a resource, and that resource have to be mined/gathered/farmed before some craftsman could make the item. Stuff would stop magically apearing in shops every 48 hours... everything would have to find it's way there through a character's action, player or non-player. NPCs would need to spend money, make money, and provide for the economy or end up begging in the street. Gold would be a limitted resource... not an ever growing unbounded plague on the earth. People would barter, out of necessity, not out of some gimmick.
That's what I'd change if we had machines that could handle it.
Agreed. However, I think that some degree of working economy is absolutely possible. It would be as simple as an NPC instigating trade with another NPC, albeit it might be necessary for the items bought by an NPC2NPC trade act to magically disappear to keep at bay an overencumbering list of "trade memory" on the given system. Also, it'd be great if an NPC is forced to seek out a daily job to make a little scratch for the necesitties of life: food and drink, a bed, some clothes.
Food for instance; that magical bread should stop appearing in their hands, especially when all they'd have to do is chop one bit of firewood to buy a new slice of bread every day: The bread doesn't need to be permanantly cached, as soon as it is eaten a timer would start counting down to the next food "push" removing the need to cache the one piece of bread they just ate. The push would reset the daily cache that says the NPC has eaten. It should be possible to implement something like that without evertaxing 7th gen consoles, or especially current gen PCs.
Thought the Sims 3 and TES:V are worlds apart, there's a wonderful mod for the Sims called the Twallan Story Progression mod which instigates a minor world economy where all the NPCs have coded "push" to build a better life for themselves. They seek out new and better jobs if the current one isn't covering the house payment, they shop for food, they aspire. And every day, it resets. A new push occurs to feed themselves, make sure work is covering expenses and to keep on progressing in the world.