My reponse is that it doesnt have to be listed a major selling point because it is already largely considered a given for big titles and something people simply dont expect from smaller ones. Therefore there is no reason to "advertise" it.
As a side note, I think Dark Souls has some of the best narrative in modern gaming precisely because it is sharp and minimalistic. All of it is voiced and characters almost never get caught in the videogame trap of delivering pages and pages of expository lore. Even the way it handles branching narrative choice is great because it is so ambigious and it is base on your actions rather than selecting a text bubble. Obviously that game series has a very different tone than what Obsidian would probably be aiming for. I am just bringing it up as an RPG that I think does an excellent job playing to the strengths of the medium.
you are fixated on dialogue. There's many thing planescape conveys through text that you couldn't convey through visuals or audio.
Just like you can't translate a book into a movie and convey exactly the same thing.
Choosing the right path instead of the left one is just as binary as a text bubble btw. Neither is more interactive or contains more depth. Just like making a choice when you have no information is no more meaningful than making a well informed choice. You just have a different approach.