You often find that it can be handy too have gnome installed even if you don't actually use it. It can save a lot of hassle when some apps that aren't WM/environment dependant, just happen to use the various parts of gtk and it's libraries.
Plus, I've found that most of the gnome apps work fine under kde, whereas this doesn't seem to be quite the case in reverse. I suppose that I could sort it out, but to be honest, I've tried to learn gnome about half a dozen times, and I always find myself returning to kde - it feels more intuitive to me.
The apps I'm thinking of, are things like grip for cd ripping/playing, gftp - which I found was easier for me too use than kde equivalents. Stuff like that.
Sure, if you're very tight for partition/hard drive space, then you may need to just investigate re-installing the gtk stuff instead of all of gnome - but hey, this is linux, so thats _YOUR CHOICE_ !