I too was surprised to see Qt4 bindings in KDE sources instead of CPAN. Since KDE 5 was released this summer, but last update of Perl-Qt was in November and involved something about KDE4, I guess that this binding will be slowly dying, too. But at least it's usable for now, while Qt5 still deals with font issues (all fixed in 5.4) having reached third minor release: surely, but slowly.

Speaking about usability, at least 480 people regularly use perl-qt4 it and 7124 have it installed for some reason, despite the absence of packages depending on libqtgui4-perl (pyqt4 is 20 times more popular, and there are approximately 97 packages depending on python-qt4 while not being a python library; pyqt5 is not so widely used as of now).

Your point is proven, but, still, I think that installing Qt module from KDE bindings is a lesser mess than employing Python as Qt GUI "driver".