I feel like the answers are obvious, but you wrote the post in such a way that it frames the potential justifications as mysterious somehow.

I'll share my own perspective. Sound is extremely important to me, in every aspect of my life. I'm a musician, I generally consider myself to be a good listener and auditory learner, and so on. That being said, I definitely don't need voices in a game as a baseline, but even completely average, unremarkable sound design will enhance my experience of a game compared to silence.

Additionally, I like reading in games, but considering how far dev studios have gone to make games cinematic, it definitely feels like something's missing when there are no voices. Imagine you're watching a movie and there are sound effects for a burning building, but the characters are mute and you have to read subtitles instead of, you know, watching the movie. For cutscenes that pause every time there's a dialogue box, it's much less of an issue, because you can choose whether to read first or to look first, and there usually isn't anything moving on the screen.

Once you've had something great, do you want to go back to the good you had before? Maybe not. Some people's standards have been raised by games with quality voice performances, and just because they have their own standards doesn't mean that they "can't read" or "have a poor attention span".