HP vs AC - for shammies

[Spitty]

Why can't we have both?

I have six or seven slots I'll swap out regularly for hp/mana/AC depending on the situation. Self buffed, I'm variable between 2100-2400hp, 850-950AC and 2400-2900 mana.

AC is helpful when tanking shrooms/juggs/prot/etc, and 100 AC makes a significant difference - especially without frontal bash immunity. Mana is helpful when you're doing one encounter that calls on having a larger pool to blow through, and little opportunity to recover mana during the fight. HP is obviously helpful, for obvious reasons.