As I want a minimalistic and fast KDE desktop I don't need these and therefore included them in package.provided. I've been gladly using kde without these packages for a long time now. The splash screen option just doesn't appear in the Control Center, and that's the expected result. And kpersonalizer just messes up my configuration, it's worth for nothing and it will be left out from KDE-4 anyway. (Or maybe not: http://wiki.kde.org/tiki-index.php?page=KDE+4+Application+Cleanup ) But if needed, these could be emerged directly though... Thx.
For the most part of the users, startkde is supposed to have those two; package.provided is what it's supposed to exist for who wants to tweak things out of the standard "sane" defaults.
I accept that. Maybe I'm the only one who finds them useless. But it's a pity, that I have to modify the package.provided file every time a new version comes out.