Yes, one thing I've considered that may make melee mage more useful is to increase the usefulness of energy steal/energy drain, and moonlight/starlight. As it stands, mages don't get a useful MP restoring WS until quite late (66 for SMN and BLM, 70 for WHM and SCH), and by then it's well ingrained that mages are not meant to melee. On top of that, all of the WS would have to be useful enough that a mage wouldn't overly hurt their party by meleeing instead of resting. Otherwise, even with good melee gear they might be discouraged from meleeing simply because doing so means they cannot do their main role effectively.