Why do you keep on insisting tanks to have cleric stance-like stat switching. Cleric stance works entirely differently from you want to achieve. It swaps MND and INT, 2 stats that affecting either magic attack power and healing power, respectively. Your suggestion is waaaaayy unreasonable as it is trying to swap an offensive stat to a defensive stat. Mind you, MND is not a defensive stat as it increases the power of your healing magic.

Please. Stop. Suggesting. Tanks. To. Have. Cleric. Stance. Stat. Switching.