I don't see how having voices remove from unique dialogues options. Nothing prevent FO3 characters from speaking their lines or Skyrim from speaking their lines. Dialogue options and choices are much more of the dialogue wheel, not voice protagonist. Even within the dialogue wheel, most of Skyrim only have 1-3 options. A lot of conversation only has 1 option, picking it letting pick another 1 option in the dialogue. Fallout 4 actually allows you to express the emotion in how you deliver that one dialogue options like angry, sad, happy.
I find more immersion with voiced protagonist because I'm not just waiting for the NPCs to just passively speaking to me, I'm actively a part of the conversation.