I should say that K3b 1.01 is installing with correct pathways, such that they are listed in Multimedia (K3b) and Settings (K3bsetup). I wouldnt want to lose that feature by paring down the package.
May I ask why that's so important? I never use the XFce desktop menu much anyway, preferring to have launcher groups for my most-used applications on the Panel. If you want them in the "start" menu, it's not much trouble to put them there yourself.
I agree that a cleaner package for K3B would be nice because I think lots of users would like K3B without all the rest of KDE, but it's low on my priorities list. Downloading just kdelibs and k3b and installing them with installpkg and ldconfig is pretty easy.