I discussed this on emacs-devel at this link:
http://lists.gnu.org/archive/html/emacs-devel/2008-10/msg00696.html
David De La Harpe Golden's analysis seems correct to me:
No. but is it desirable to? If emacs says "monospace" to the OS, and
the OS returns something usable (see below), should emacs second guess
it? The distros with ttf-georgewilliams packages seem to be aware of
the issue and are fixing it by removing or renaming the font in favour
of the de-facto standard "monospace" virtual font name
https://bugs.launchpad.net/ubuntu/+source/gw-fonts-ttf/+bug/95357/comments/6
So, we should probably leave things as they are. I'll add a note about
this to etc/PROBLEMS.