I think if you have voice prompts it is also how you use them, i dont need a elaborate welcome - brand commercial - weather forecast when the camera boot, a simple sound will be fine for that.
But higher things like also mentioned i can see voice being nice as a table of 10 - 12 different beep sounds are hard to keep track off, not least if it is for features / options you do not use regularly.
I also think the people having problems with sounds / voice are people that like things very stealthy, and i can also understand that but personally i dont need a dashcam to be quiet as the grave.
I do think they could be simplified, so instead of wifi enabled / wifi disabled, it could just be wifi on / wifi off. Though i dont think i would use it much myself, ideally you should be able to customize your voice files.
So the voice files could be on the memory card named 1-2-3-4 ASO each for its own feature, so say instead of 4 being wifi on.MP4 you could make your own recording to replace wifi on.mp4.
so for the hell of it you could make wifi on be a fart sound, and wifi off could be laughter, EMG recording i might change to screeching tires sound.
I am a huge fan of empowering people to make their own choices / changes, but i must also recognize that people dont need a say in everything in the world, so if thats impossible or just not worth the trouble to implement in a dashcam i accept that.