Maybe I was wrong to complain about resource runes being underpowered. I'm talking specifically about the wizard runes for reducing AP cost of certain spells. I can't remember what the numbers were before but now I'm certain that resource runes are in fact overpowered with respect to damage-increasing runes, at least in the following two cases:

Meteor: 250% damage + 100% damage over 3s
-costs 60 AP

"molten impact": 325% " + 130% "
=> a 30% increase

"star pact" : costs 42 AP
=> this is a reduction of 18 AP cost, which is 30% of the original AP cost. However, this means star pact can be cast 1/(1-0.3) times as often, which equates to ~1.43 times as often. A 43% increase in usage.

There's a similar thing with arcane orb

Arcane Orb: 250% damage; 35 AP cost

"obliteration": 325% damage
=>30% increase

"tap the source": 23 AP cost
=>34% decrease in cost; 52% increase in usage

Naturally, I believe Blizzard's internal build will not have these errors. Overkill makes the damage option even less enticing, so if anything, the damage increasing runes should be overpowered relative to th resource cost reduction runes.