That standard was widely accepted due to the FSF, if not actually created by them. It's by no means a Unix standard. I'd be hard pressed to expect Sun to cooperate with the FSF, an organization with goals pretty much diametrically opposed to Sun's own.

And the xterm example is not restricted to xterm; it's the way all Xt apps are expected to behave.

That being said, it would be nice if it supported what everyone expected, they break their own ``Command Syntax Standard'' (from intro(1)) by allowing multi-character options at all, and it's not like Java predates the widespread acceptance of GNU software.