6 years ago, you could simply install xfc4-panel - or any other XFCE package - individually without too much fanfare. It would happily install and run no matter what WM you were using.
These days, trying to install xfce4-panel individually is impossible as it will force you to install an army of "additional" packages, some even originating from GNOME.
XFCE is not the same "lightweight" desktop environment it once was. That task is now handed over to LXDE.
In the meantime, GNOME and KDE have moved on to something else: shiny, full of animations, and resource-hungry. I think it's only natural that some other desktop environment has moved to fill the void where GNOME 2 and KDE 3 used to be. LXDE now fills the place where XFCE used to be. Sooner or later, something else will fill the space where LXDE used to be, etc, etc, and life goes on!
I can't find anything GNOME-related here, unless you are talking about GTK (which you probably would already have on your system if you want the xfce-panel).
XFCE is not the same "lightweight" desktop environment it once was. That task is now handed over to LXDE.