How many times has Microsoft promised patches that don't require a reboot?
I think it may have started with Vista.
I suspect that the reason reboots are required as that's the only way to refresh stuff like the kernel and the .NET engine which, I'm guessing, are pretty difficult to shut down entirely due to how many lower-level utilities lean on them.
The downside of hot patching is that Microsoft occasionally releases patches that break things, and I think even pedestrian users are a bit gunshy about patching immediately upon release.
