The kernel move was, reportedly, for performance reasons. I think if you use NT workstation at the time, you'd probably notice this compared 95/98. I believe MS also runs http in kernel space under http.sys. There's no backwards compatability there for legacy 8 or 16-bit apps as, you know, the web is younger than those apps and even then a browser would not need to interface with them.

I think MS is eternally hamstrung by performance and legacy issues because those two things are in demand for so many of their customers. Windows fits this market, which is fairly sizeable. Of course now with hardware at the speed its at, you can get a lot more slack. I've found the linux desktop to be horribly slow until the past couple of years where there's a glut of CPU/GPU performance on even the most commodity equipment. I can run, and have run, Win7 on equipment that shipped with XP and its been a fairly pleasant experience. Running, say, a gnome or KDE WM on that equipment is a nightmare. MS, for all its faults, is fairly conservative in many regards, especially performance.

At the end of the day this is yet another security issue that needs to be patched. The larger issue in my mind isn't MS decisions from 15 years ago, but why so much of our software infrastructure is being written in languages that more or less beg for stack/malloc vulnerabilities. These constant tirades about MS are just more "the beatings will continue until morale improves" and not really a constructive conversation about security. I think in the near future we'll be looking at all our stuff written in Rust-like languages and wonder why the hell it took so long to do.

Lastly, Win10 is a technical preview. Finding bugs is exactly what should be going on here. Are we really being this critical on pre-release software? I don't see any other software held up to such a standard.