I don't mind that as xquartz is miles ahead of the X11 thing that is in OS X itself. Xquartz is an Apple project anyway. As long as they keep the UNIX base I'm fine with changes like these. With the UNIX base you can install all these kind of things yourself.
GIMP uses a separate windowing layer, the X11 windowing protocol, on Mac OS X, which must be installed first. The XQuartz project provides this functionality. There you can download the most recent version of X11.app.