occasional, you'd be happy using a browser that can't access most of the Internet in a usable manner then?
That's the gaping hole in your desire for no change. Many other things move on so your OS needs to as well to keep up.
Remember Win98 and it's security model (or lack thereof)? Would you seriously wish that on anyone in this day and age?
XP might be frozen, but it doesn't mean support costs are nothing. Age doesn't mean no new security flaws. There will be some cracker flaws "released" post April.