The black mage argument is just silly. Black mages ARE NOT ELEMENTALISTS. Unless you think that spells like poison, sleep, demi, toad, pig, death, etc are elemental somehow. The reason for having so many elemental spells in their repetoire is that elemental magic has been the primary type of spell damage throughout the series.

Also, if you're still going to make that argument, you can't do so while completely ignoring the fact that con also gets all of the 'traditional white mage spells' like the various cures and buffs.

The main issue is that people need to quit trying to pigeonhole conj and thm into white/black mages. Neither class was divided originally along those lines, and you can make a case for either class going either way. Personally, I think SE should just make it so that getting to level 30 in either class unlocks both.