Actually Policykit is not that hard the first time I used on Fedora 11. There are front-end (System->Preferences->Authorization on Gnome desktop) that allow configuration and fine-graining control unlike sudo (I have not for a long time because it is not a long term good choice).
Because that front-end is gone on Fedora 12 I have to relearn the policy setting from terminal (or using text-editor). The good thing about PolicyKit (Polkittool) is the ease of use and human readability.
Selinux has tremendously evolved. it is very easy to submit bug report so policy can be updated as soon as possible.
Packagekit is not hard at all although it does not have yumex complex functionality. However the ability to detect missing codec, fonts and the fact it is backend independent (yum, apt-deb, smart, conakry) cannot be overlooked. Because of my design field, I mostly use it for simple update and use yum for advanced function.
I think the biggest problem in this community is the fear of change and inertia for some traditional users. Let not forget Fedora is all about cutter technologies.