Another advantage of SWT is that GCJ supposedly works with it. (Has anyone actually tried this?)
It may be desirable to actually use Java in a slightly different way and actually create executables that are seperate from the virtual machine.
It would be VERY cool to be able to do the same with xith3d/jogl and create an application separate from the JVM.
This would not be possible with AWT/Swing (yet?).
This is somewhat interesting and related: