In my opinion, Balance does need more defense and the best way to do it is just restore some of the passive mitigation moonkin form used to have. When moonkin form first came into the game, it had close to the same armor modifiers that bear form had.
Over time the defensive value on moonkin form has been nerfed into oblivion. A spellcaster should never be forced to silence themselves by going into bear form for defense. Bear form isn’t ice block or turtle. Lowering your damage to zero isn’t a fair trade off for the defense or recovery Bear offers.