Mainly for faster leveling. WIth an enchanter you can run into a room in L Guk, AoE Mez every mob to lock them down and take them out 1 by 1. While they are AoE mezzed you can single mez them to make it last longer and reapply when needed. YIt's just too damn good not to use. Around level 40ish is when shaman starts to get real good so that's why I'm swapping to it. The shaman trio is literally unkillable and does great damage. You have paladin's LoH, it's AA to slay undead, high AC due to plate armor, you can dual wield, monk FD and feign, shaman buffs, heal, HotS, Puma and DotS. Using enchanter with PLD/MNK is better for leveling and clearing plane of Sky. The adds can be a pain and using a chanter for AoE mezzing and charm trivializes the encounters. But for bossing and everything else shaman is where it's at. Better survivability and damage.