Here are just some things i think.

Really like the contextual roll out in the world. Moving rocks and trying to figure out stuff to get to secret areas are so much fun.
I would like a "ping" system in multiplayer to show everyone what i want them to se/focus on. Since it is a pretty big world with lots of secrets that would be cool instead of giving directions that always end in "your or my right?".
Quality of live things that i would like is a marking system to sell/give/take multiple things, instead of one item at a time.

Finally something that i personally would like to se. Some extended gore system, like chopped heads, exploded bodies, contextual damadge bodies (lightning,frost,force,fire etc) and show that killed them and giving them a unique look.
I played some D&D and all of my DMs gave detailed events in and out of combat whenever you succeded or failed. Especially in combat, i would like a "finishing system", when you score a critical hit or just doing the finishing blow a contextual animation plays with that respective character killing with a fancy animation. If you are a wizard them you do some kind of incantation and burn someone to cinders, of you are a warrior with a two handed weapon you cut them in half etc etc. Think Dragon Age orgins animations, or Witcher 3 finishing animations.

Just some suggestions, would love to know what you all think.