Motif just came out with a new version
Check out
www.motifzone.org
Also, Motif is opening up, but there is the free LessTif, too.
The reason big companies are moving away from it are not technical, it is bandwagonial.
Sun made a very bad desktop made on Motif, the current CDE, and it is so bad that they thought it easier to adopt GNOME instead of clenaing it up or reimplementing it on the new (THEMEABLE!!) Motif.
However, if your processor is a slow 1Ghz or even a darns slow 750MHz Athlon, don't expect any of the desktop bloats to impress you.
My fastest x86 processor is a 500MHz Celeron, so anything but Motif is out of the question for me.
There is also Athena.
Why does Motif not die? It is required for Posix compliance, it is built the 'Unix' way - Gtk and Qt are both Windows-centered, Qt maybe more than Gtk.
There is also xforms, with fdesign, that one is as easy to use a BorlandC for WhineDoze.
Personally, I will not use a toolkit that does not have Unix style resource files.
But, I guess you d00ds start to know me by now