I highly respect the time and effort that was put into what is clearly a massive and highly detailed game, but It'd be fair to include a no-voice option for the protagonist and full text in the dialogue options (like in Fallout: New Vegas).
One of the game's selling points (aswell as a trademark of the series, and Bethesda in general) is freedom, being able to create any kind of character we want.

Not having a voice means you can imagine any kind of voice, accent, tone and personality you want, create and roleplay a limitless number of completely different characters, aswell as interpret a dialogue option differently, depending on what the character you're currently roleplaying is like.

It's also great for immersion, it makes it easier for players to put themselves into the game and experience the amazing world first-hand. Personally exploring a new world is what they are going for and a "silent protagonist" would add to that feel.

There's plenty of yearly releases for players who want cinematic, fully voice acted experiences, while fans of games immersive, roleplay-heavy experiences wait for years to get our hands on precious treasures like Elder Scrolls and Fallout games.

Voice acted protagonists have their place, they fit well into cinematic games, but silent protagonists fir better into RPGs that focus on freedom, which is what Fallout is and why fans, such as myself love it. I think it is far, aswell as smart to give us the option to play the game without a voice. Adding a voice removes much of the roleplaying potential.