BLM isn't as popular as you'd expect. The class is rather different from what you'd expect of a typical MMO mage-class, and doesn't really strike many as fun. Additionally, for the moment, the Bard is superior in nearly every aspect. When it comes to what's in demand as far as groups are concerned, then tanks are first - particularly the Paladin, followed by healers. When it comes to DPS, Bards are the most sought after, and then everything else after that is more or less on equal ground.