The issues isn't pkgbase itself, rather it's the deprecation of traditional updates. The design philosophy of pkgbase might work in an embedded system, but package based installs have caused me nothing but trouble on every Linux distro ever. Also, why choose KDE of all things‽ I get it's easy to use, but why not also provide an option for CDE or twm?
Everything below is my opinion. Agree, disagree, tell me I'm an ID10T error, all good.
I'm not sure that "pkgbase on FreeBSD" is an apples-apples with "...on every Linux distro ever".
Deprecation of traditional updates: For a long time "traditional updates meant upgrade from source".
I can visualize "freebsd-update" evolving into a script that does the appropriate pkg command for pkgbase. Would that satisfy your requirement?
KDE: Again, I have no dog in this fight, but anything that has ever installed a GUI/DE everyone argues about what it should be. Why are there so many Ubuntu distros? Because KUbuntu installs KDE by default, GUbuntu installs Gnome2 by default, etc. I don't know how many people don't want KDE, install KUbuntu but then wipe and resinstall a different distro instead of just installing a different DE.
Why stop at providing an option for CDE and twm? I want WindowMaker as an option, others want XFCE4, some want awesome. Slippery slope appears.
Everyone of us that has been around for a while understands what we need to do.
Maybe I'm naive or just been around for too long, but sometimes, it's not bad to just wait and see what happens instead of panicing.