Well, I don't know what 'de minimis' is in
your opinion, but surely
when we want others to keep to the GFDL, keeping to it ourselves would
be the first thing to do. If we say it's okay to break some rules of
the GFDL, why not others? If it's okay to not make a title page as
required by the GFDL, why is it not okay to not include the full text
of the license?
It all boils down to "the spirit of the license". As long as we don't
violate the spirit of the license (which we don't), we should be fine.
If not legally, then at least morally.