I agree. In both of my playthroughs I have a character set to perform magic more than anything. Fran in my first file and Penelo in my second file. I've found them both to be very useful. Aside from the obvious fact that some enemies are weak against certain elements, it's also very useful for flying monsters. Rather than have a ranged weapon equipped, I just have one of my non-mage characters cast Oil and have my mage cast Fire magic.