They are the core part of the gameplay feature that will be introduced in the future. Aside from that, story wise, not really.
alright, I have played other games where the character has something talking in their head. IMO it can get a little exhausting to read if the voices are present in every conversation. if the voices are only for certain situations, like when the MC is alone it is much more bearable. I like the game so far, keep up the good work!