Dragoon is actually pretty great at Frontlines. They have the best burst damage in the game and that is what it takes to kill someone that is getting constantly healed. I can see monk having a problem, but if they are good enough to keep Greased Lightning up then any other buff to them would make them too powerful. I'm sure a monk with Greased Lightning III can keep a healer on lock down with actions every 2 seconds all while doing pretty good damage.