Hi Ninthace. I don't disagree with anything you've said. But I do think I look at these things from a different (and very simplistic!) angle...
The basic problem with operating systems such as Windows is that no one alive knows how they work because they've become too complex. Put simply, unlike (say) a F1 car engine, there is nobody who knows exactly how Windows 7 works.
Back in the good old days, I used to program in Z80 assembly language as well as pure machine code. I could read the disassembled code of a Z80 computer's OS (Spectrum, Sharp MZ700, RML 380Z, etc.) and see exactly what it was doing. I could write code that did precisely what I wanted it to (and only that), and was as compact and efficient as possible.
But things were much simpler then and they got infinitely (almost!) more complicated. As I understand it, Windows is compiled, which in itself makes the OS extremely bloated and very slow, and I'm fairly certain it's been created by a very big team of programmers. And as I said, no one person actually understands how or what the OS is doing, so problems are patched as and when they're reported - which, 10 years later, is still work in progress (or rather, it was!).