There are common programs you need to install via the terminal
Out of interest, which programs do you need to install via terminal that concern the average user?
you can’t even change sound playback quality without editing a conf file which requires sudo!
What do you consider changing “playback quality”?
Sampling rate? That can be changed in a config file without sudo (~/.config/pipewire/pipewire.conf.d), you shouldn’t though because many applications expect 48000 as sampling rate. Unless you’re doing studio recordings you want 48000.
There is so much you need the shell
Correct, there is a lot of need for the shell, for power users. I don’t really see anything that the average office and browser enjoyer needs to do in the terminal. You can even game now in most distros without opening the terminal once.