I can clearly remember a time when I was trying to streamline my UI when I experimented with turning off as many names as I could. I hated the lack of information; in fact, it was shortly after that that I went out and got my first tooltip mod. I suppose my change of heart the other day was due to my relaxed engagement in zones where I was in absolutely no danger. (It wasn't even a PvP realm.) Still, it struck me how pristine the experience of making my way through the zone and through town was. Was I headed in precisely the right direction? Who was this woman? Did that fellow over there have the herbalism supplies, or was it something else?
I'm guessing there are roleplayers who partially or completely turn off their UIs in town on a regular basis. Do you? What about out in the world, when you're adventuring? How minimal could you go and be effective and have a good time?