One thing about having to install Xorg to support an extension is that then you have to use Xorg as your X server. I could be wrong, and their could be a workaround to have Xorg installed for it's libs and use Xvesa for X. So it is not only a size issue having Xorg in a dep file. Don't get me wrong, I like the use of Xorg being as trouble free as possible. The same situation happens with alsa as when alsa is installed the modules of the alsa module extension gets loaded and prevents the easy use of OSS. That is why libasound exists to not require the use of alsa to make use of it's shared libs that are needed for some packages, like Firefox.
It was mentioned that the next upgrade to Xorg would be more modularized, but in the mean time I think that the shared libs needed to run Xfce and other such apps need to be available in the Xlibs_support extension. That, or just simply create an Xorg-libs.tczl extension that would be a dep of Xorg. I saw another small distro that has most if not all of the Xorg libs in it's base though it uses Xvesa for it's default server. Of course, I don't want more X libs in base but rather they be made available in an extension outside of Xorg. I will get together with Curaga and see if there is an agreeable plan in regards to seperating the X libs into it's own extension. I am not on TC so I don't know just how much space the Xorg libs would take up, but the current Xlibs_support is only at 25kb or so. Even a 1 or 2 MB lib extension would be better than having to download a 25MB extension and force Xorg as your X server.