Perhaps the GNOMEs might want to make it easier to develop for what exists now before abandoning all that to go chasing the next rainbow.
It is all well and good that GTK+ does the automagic binding thing to every known language. Better still would be documentation on how to use ONE of them. If you were trying to bring up a new programmer, what documentation would you use?
I have beat this one to death here in the past but it really can't be repeated enough. Documentation is as important as code.
I can find a basic programming in Python + Gtk document. But Gtk != GNOME. It won't show you how to get full i18n support, attach to dconf, dbus, etc. It won't show you the 'right' way to produce a program that complies to the GNOME coding standards, leverages all of the current GNOME technologies and will have (perhaps) a shot at running with the next version with minimally invasive changes.
Perl? Java? Only very old very outdated docs. C of course has the reference docs... but you better like reading em on a web browser because you don't get a local copy in devhelp anymore. And it ain't written as a tutorial.