Uninstalling Firefox means installing KDE

I'm running Ubuntu with Gnome-shell. For reasons outside of this question, I needed to temporarily uninstall Firefox. I had no other browser installed at that time. On entering sudo apt-get remove firefox I was told that doing so would install about 100 packages, mainly associated with KDE. I aborted the command and installed Epiphany; then I was able to remove Firefox without installing KDE.
I find this strange. Apparently Ubuntu wants me to have at least one browser installed (why?) and if I don't, it wants me to install all (or most) of KDE. How does this work? If it is absolutely necessary to have a browser, why not suggest Epiphany?
This is Ubuntu 13.04 with Gnome 3.8 added. It is not a clean install of Ubuntu Gnome but I have certainly never installed KDE.