If someone uses a compromised OS, they already have problems, with or without a camera or microphone. Let those who make trouble for themselves (by installing silly OSes or otherwise) do so without us worrying unduly about making even their stupidest actions safe -- it is not worth the effort for us to cripple the device too much for safety (or even spend time thinking about Windows and Android).
I have argued elsewhere that the use of software (outside a sandbox), and indeed hardware, involves an element of trust unless one audits everything oneself. I am lazy, so I choose to trust certain software not to betray me, particularly that software which is theoretically easily auditible and may well have been investigated by others, so FOSS is more likely to get my trust than other software. Some software, though, I strongly expect to be suspect, including most proprietary/partially-proprietary/single-entity-controlled software, so I avoid them: this includes Windows, Mac OS and Android.