Why is the average total so low? Also, it says that with +100 AP I should see an change of +0 damage.
Because heroic strike replaces your next melee, and avg total will be the amount you gain by using heroic strike. AP doesn't affect the heroic strike bonus.
So it's intended? Seems a bit odd. Shouldn't the number on the actionbar reflect the average damage done by this attack, counting in all variables (which is what theory craft is all about!), like the current weapon base damage?