I agree. Microphone On/Off should be in the Video and/or Pro Video App.
I like to shoot timelapse videos but I don't like the limited options in Hyperlapse. I shoot normal video, sometimes several hours, and then use a video editor to adjust the speed and create the timelapse. Yes, it's just as easy to remove the audio in post but I want to turn off audio when recording to reduce initial file size.
Here is a work around:
Add microphone to your Quick Access Panel
"Turn off microphone access?"
"All apps will be blocked from using microphone. Apps will still work, but they won't be able to access any sounds from the microphone."
This disables microphone for all apps including phone so you must remember to turn it back on. However, if you try to use your phone with the microphone disabled, it will ask you for permission to turn it on.