They've already gone with the cinematic path for dialogue though. At this point having every character be an active participant except the MC, who's just a mute observer, feels a bit jarring.
I agree that currently lack of PC VO is jarring, especially that they attached hilarious animations to him/her anyway. I read that they will have full VO, and I believe them. It makes more sense to me with their current design, then not doing PC VO. Even if they won't do it, it won't alter existing decisions, so 🤷. Might as well have that VO so streamers don't have to do their own reading.
But from a purely theoretical point of view, if we were to keep PC mostly silent the simple solution would be keeping camera away from PC - there has been plenty First Person RPG with a silent protagonist and it works wonderfully. But yeah, cutting back to silent PC in otherwise fully voiced game has been awkward since KOTOR.