Well, if you say that Mint linux is no more than Ubuntu with some modules, then you are somehow mistaken about it...and If you say this about Mint KDE, then you are COMPLETELY WRONG!

A Linux distro isn't only about an installer, and derivation became really a standard way to have new distros in Linux world.. The modular nature of GNU/Linux systems makes derivation a matter of selecting, adding and removing packages, then add some more of your own tools if there are any..then you got your own distro... I know this isn't always the case as some distros does provide some new ways of doing things(like package management), but this doesn't make the distros which doesn't do so a 'clone' distro.. A good example for this is SuSe which started as slackware derivative but borrowed the package system of Red Hat(RPM)..
Another example is SimpleMEPIS, it's compatible with debian packages(a derivative) but is completely a stand alone distro..

Mint Gnome provides many fine tunes and add-on's on Ubuntu, and although they share many application selection(like firefox and openoffice.org which are standard recommended selections), it does pick its own selections for some categories(like Amarok) ..I think for a desktop PC OS, this should be the case..

While this is the case for the Gnome Mint, for the KDE Edition, this is even more obvious. Just compare this edition to Ubuntu and Kubuntu and judge your self !