Your pro-moogle campaign is mostly true.

What you said about Black Mage Moogles really does not convince me that they are worth having. A Moogle leveled as a Black Mage is a Moogle that has sacrificed it's versatility only to be doomed to excel in gimped offensive spells for the rest of it's miserable life. Ultimately, the only Moogle class that reaps any benefit from Magic power is the Black Mage (Well ok maybe Time Mage too, but only for one spell), which is clearly a slot on the battlefield that can be put to much better use (As you have proven!).