Actually it’s cheaper than blade barrier kiting. You aren’t dependant on the A.I. pulling out the phasing/burrowing/teleporting/ranged combatant nonsense and you kill stuff faster.
For most casters it’s better to kite stuff around because they don’t have the ability to survive for too many hits (Generally this applies to Arcanes) or their particular AoE only procs on a moving target (Blade barrier) This isn’t the case with druids. A druid has the option of the arcane spellcaster’s persistant AoE with the divine caster’s ability to fight.