I can see why some things have restrictions...

Would be kind of silly to see a Black Mage in Heavy Allagan Plate, for example. Or a White Mage in a hoodie with the Darklight plate armor. But anything short of suits of full plate (And job-iconic gear, such as the AF armors, not including the crafted gear) should totally be glamor-able. I was so disappointed when I learned I couldn't wear my Alchemist coat as a BLM.