Does anyone have a one-paragraph explanation of why this choice was made? I usually don't install the kernel-sourcecode RPM (née kernel- source) since I don't want an additional 100-200MB of stuff on my disk if I can avoid it.
It's not shipped for much the same reason that you don't usually want it; it's not needed for most people and it's duplicating information available in the SRPM:
See Arjan's brief explanation: http://www.redhat.com/archives/fedora-test-list/2004-September/msg00923.html
But every so often, I have to install VMWare or some other software that wants the kernel source to be installed. "up2date kernel-sourcecode" has been a fantastically easy way to do that without have to learn arcana.
This may be more complicated for a while. When they update to use the new build system, it'll work just like before except you won't need to install the huge kernel source RPM. This is a big win long-term.
Paul.