Agree with topic creator in some way. It is actually not that ruining the immersion process, but just quite odd to have muted MC in dialogs and suddenly speaking while in camp, for example. Many cRPG's implementing voices for MC just for shouts in battle, but if we have normal speech implemented, why not have full voice lines?
Of course it will be titanic and hellish a work and tons of money, because you will have to record AT LEAST 18 different voices to ALL the dialogs in the game (9 for all the alignments x 2 for male/female). Horrifying amount of work there. But it will be legendary, i would say. And there have to be an option to have muted version ofc.
The hard way to fit all the sides.

As for me, since it is still not the irl d'n'd, where everyone choose their own words to speak, etc, the game is much more like a story, where you're choosing between different options of the plot, like a number of books, where you can jump from one to another and they will compliment each other somehow. So, i prefer to have full voice acted MC.

Another interesting aspect: we will have opportunity to play companion chars, so, will they be acted? Or got muted just like a custom MC and lost so much of their charisma and personality. If so, i guess i never ever start the game as any of pre-created characters.