>I think great RPGs let you tell as much of the story in your head as possible
I'd say that having to tell the story in your head is a sign of failure on the part of the game. But, for an open world sandbox RPG, so is restricting you from enacting whatever story you want and we don't have the technology to avoid both.
One of the most successful games of all time is Football Manager, which mostly involves staring at spreadsheets of numbers about football players. But it's also one of the most immersive games ever! Give me space, freedom, and simple tools to build my own narrative and I'll be more engaged than listening to the most soaring dialogue you might be able to write.
I'd say that having to tell the story in your head is a sign of failure on the part of the game. But, for an open world sandbox RPG, so is restricting you from enacting whatever story you want and we don't have the technology to avoid both.