If the code were open, Microsoft wouldn't have to be on the ball, now would they? You or I or self described 'computer gurus' like the OP could write our own patches. :)
Programming? I can barely keep up with Java. Patching an OS is beyond my capabilities. True, someone would author a patch, but I tend to be wary of third-party anything. Of course, when it comes to Microsoft, you have to be even warier of them...