Here's my list:
Fewer unkillable/essential NPC's. Questgivers should be neutral NPC's with no impact on the story. If some "boss" character just happens to be near you and talks shyt, you can kill them right there instead of waiting for some big fight later.
More interactive interiors, buildings etc.
Complex decision trees where your choices throughout the game have an obvious impact both DURING the game and how it ends. Kind of like Witcher 3 but expanded.
For tougher games, less input reading. The enemy on the screen should react to how your character moves, not the button you press. If I press "X", the enemy shouldn't immediately react until my character actually performs the action associated with an "X" button press.
For open world games, there should be freedom in how you tackle an objective. Like GTA, if I want to take down a mob boss, I shouldn't have to get into some pre-scripted shootout. I can stalk his azz and follow him to his mansion and then murk him. Basically combine Hitman and GTA but with the detail of an Elder Scrolls game.