I don't dare to imagine how the size of the game would increase in GB and its budget if a game which is actually laying value on dialog instead of just slicing and dicing action.
Besides the difference between reading/listening and varying speeds from player to player, with every piece pre-chewed for us like an assigned voice to a character in our game does take a bit of our own imagination away like the actor in a movie representing a hero from our favorired book but has a voice which does not match the one we ever had in our head for him.

Ideals are like stars. We might never reach them. But we can set our course by them.