I'm going to guess the hardware switches and key combos went away because they are too confusing for users. I remember constant complaints of "Internet doesn't work" because the wifi hardware switch was turned off. And as the saying goes, if the majority of users are using it wrong, it was designed wrong.
I think Apple picked the right middle ground by making access to the mic and camera a permissions request as well as showing a clear indicator to the user whenever these are active. Steve jobs said the best UI is to ask the user for their data when you want it and keep making them aware of this access every time you use it.
The problem with software-controlled permissions is that nation-state actors (who have unbounded resources) can snoop on your private matters with significantly greater ease.
At least with a hardware switch, someone would have to physically intercept the air waves in the room you're in. In software, the surface for OS-level vulnerabilities is massive, and state sponsored mass surveillance just gets easier.
Sadly, this is a trade-off we have made as a society for "ergonomics".
This line of argument is bikeshedding at it's finest.
If Mossad is out to get you, they are going to get you, no matter what you do. The threat model for 99.999% of the population doesn't include bespoke attacks from three letter agencies.
I think Apple picked the right middle ground by making access to the mic and camera a permissions request as well as showing a clear indicator to the user whenever these are active. Steve jobs said the best UI is to ask the user for their data when you want it and keep making them aware of this access every time you use it.