As for the immersion aspect:
The lines are already there in the dialogue options. What you choose is what you get. I expect the protagonist to have their own way of expressing themselves, I don't want them to be entirely my (mute) puppet. I don't go control-freak on my avatars, I expect the game to do things outside my control, because it WILL do it one way or the other. This isn't table top where you yourself can verbally playact and talk to your DM, and it can never be, the concept is different.
Voice actors have done a tremendous job in this game and I trust they would follow through with the atmosphere in the dialogue. I am not actually projecting myself into my character, I am more like their guide into the game's story. And that is why their muteness bothers me and why to me they feel incomplete.
Yes, and you are not wrong to prefer that kind of defined protagonist. Personaly, when playing a game like Baldur’s Gate3 (or Pillars of Eternity etc.) I like to come up with general character concept - who that characters is, what his background is, what his personal goals are, what his plans were before he got swept in that adventure. There is a lot joy to be found in being more active with role playing choices.
To be honest, I never played a tabletop and initially I also preferred games that would do more character building for me. I gave it ago one time, I started to enjoy “role playing” more and more.
As someone above mentioned: if Larian added full VO for origins, but not Tav/Durge, I would fine with that. I suspect it would be a staggering amount of work, as I dont think lines as they are in the game could be simply read. More likely a separate script for each character would have to be written, to make it work.
