One of the most immersion-breaking features of nearly all video games, not just ESO, is that you can't be polite. Take your character for a spin. Walk him/her around town, buy a few things, run into people who know you. They may compliment you, or just say "hello."
But what do you do? Unless it is a planned interaction, the game forces you to maintain a sullen, sulky silence. After I've ignored half a dozen friendly "Hello"s, I begin to feel my mother glaring at me. It's very rude not to respond in some way but just to clam up when faced with people extending the ordinary social courtesies.
Some might object that this ability is essentially useless. But a lot of things that are said to you ingame are "useless" in immediate, practical terms. They're there to establish an atmosphere, not just to do things.
So could we have a few of them slipped into the game some day? "Hello" "Thank you" "You're welcome" and so on. Since they don't need to be scripted to some action, it would be an easy thing to accomplish. I think it would make a bigger difference than some might imagine.