Aha, looks like I've found the culprit responsible for Cinnamon indirectly depending on Qt libs :-/
$ aptitude why libqtgui4 i cinnamon Depends caribou i A caribou Depends python-pyatspi i A python-pyatspi Depends qt-at-spi i A qt-at-spi Depends libqtgui4 (>= 4:4.8~)
