#1 - In excess of 95% of all security patches/updates/workarounds implemented on a windows platform are those that come through the automatic update process
#2 - Upon disclosure, the universe of script kiddies which never, ever, would have discovered this security exploit on their own have now been handed a gift which they will exploit with their rudimentary skills.
I'm a strong proponent of responsible disclosure, and really believe that it has made our platforms much, much more secure, obviously in an absolute sense, but also, in a relative sense.
But, responsible disclosure involves giving the vendor a reasonable amount of time - typically one or two patch cycles, prior to releasing the exploit. Anything other than that is juvenile and besmirches the community of responsible security researchers.