And it shouldn't be. 19 Spirit is currently better than 7 MP5, just barely. 19 spirit gives around 7.5MP5 in combat and talented (that every hpal needs) at 80, and more out of combat.
Wow, that was fast. And, as you noticed, I meant 18 . The math is correct for 18, however.
Also, I believe the same is true for Exceptional Spirit on weapon, I believe it to be better than, if not on par with +30 int, especially if you're in the 35k+ mana range.
. The math is correct for 18, however.