Not always, no. Sometimes a metaphor is more effective.
As in your map/country example! Or maybe that was just
a lapse, and you really believe that point should have been
spelled out in literal terms?
One of the most fruitful areas for applying metaphors is
in trying to communicate mental phenomena -- as in,
that really brought me down to earth with a bump, man!
Many such phenomena can be very difficult, or even
impossible to convey otherwise, at least for people
without a college education and the corresponding
vocabulary. Personally, I'd say some things are
practically incommunicable in literal terms no matter
how good your linguistic skills. (And, of course,
those of your listener need to be equally good.)
Some hard-nosed types seem to believe the arts
are good for nothing but entertainment, but in fact
what they're pre-eminent for is expressing subtleties.
And in the gray area bordered by therapy and
religion, psycho-social subtleties can even be
manipulated -- for good or ill -- using such
techniques.
Robin