I think you are discounting a value of leaving things to player's imagination. Yes, there is an inheret limit to what player can do in a computer RPG, and inheret limit to what a game can respond to. There is, however, a difference between not being able to acknowledge or respond to player's roleplaying and limiting player's ability to roleplay. That a game can't respond to the voice of my protagonist I have imagined is to me a far lesser problem, than a game imposing a voice and intent on my protagonist.
I'm not discounting that.
But whatever the case may be, fully voiced or not. You are limited in your ability to "Roleplay" by what the game has prepared for you and thus how characters respond to what you have available to pick.
You might imagine your character saying something different to what is written, but characters will react to literally what is written.
This might grant some leeway for you to headcanon something slightly differently worded but provides the same overall meaning (I.e. What you state is illusion of choice in ME's dialogue) but you're still a slave to exactly how the writer imagined your character made the response in regards to any actual interaction (I.e. Any well refined dialogue system that isn't Bethesda-esk cardboard cutouts staring at each other)
While voiced protagonist still maintains exactly the same state as non-voiced in terms of being tied to exactly how the writer wants to portray your character's dialogue. Only you can now have much better scenes, with your protagonist actually emoting and interacting with other characters creating a more realistic dynamic experience.
The only benefit that non-voiced has, is your ability to imagine your character has a totally different voice to the one you literally picked for them and that is used for bunches of assorted lines through world interaction and combat (In BG3 at least, other non-voiced protagonist games don't include any vocalization for the protagonist at all)
