Hardware kill switches are unfortunately pretty much useless. For camera it's okay, but a tape is just as good, for microphone, even the gyrosensors can record voice in some quality. And here is the big thing: there is hardly any threat model where blocking the camera would help when the software stack is a burning pile of C buffer overflows from top to bottom. If you can't trust the software to such a degree, then you might as well just not turn on your device. Seriously, what's up with the linux userspace where goddamn gnome initial setup is a C program?! Like, we were okay with lisp code decades ago in more serious things, and nowadays we actually have memory-safe languages with very close to native performance.

But the biggest problem is the lack of sandboxing, and UNIX permissions are way too crude to be of any use. The attacker at worst can't install a video driver, but can easily add anything to your bashrc, or read the content of your browser's cache, etc.