Install InkScape without XQuartz
Not officially possible, yet&mdash;the Inkscape developers will have to remove the XQuartz dependency by switching to the native Gtk and Glib libraries for OS X, just like the GIMP team did a few years ago. 

This work has been in progress for a couple of years on a separate Inkscape branch, but there is no official release yet. However, you can download the latest DMG here (currently based on Inkscape 0.91) both for GTK2 and GTK3 (experimental), at your own risk&mdash;expect bugs and crashes.