Tonight I had an epiphany while talking with another arcane mage. He told me he prioritizes haste over hit (even though he's not capped) and mastery, and that he doesn't use Rawr. It transpired that he doesn't actually try to optimize total damage over the course of a fight, because burst damage is often more important (he cited the Spark of Rhyolith as an example) and is the arcane spec's strong suit.

On further reflection, I realized that no good raider actually optimizes for total damage when timing cooldowns -- we make our damage bursts happen when they're most important tactically. This explains why some raid leaders complain about "Recount whores", especially in late Wrath where the LK's ghouls made convenient meter inflaters.

Why not provide "weighted damage" and "weighted DPS" meters, where more important targets and phases would be weighted more heavily? We could have separate profiles for each instance boss (possibly in collaboration with the DBM team (who'd have the knowledge) and the Rawr team (who could also use the weighting factors)), and for trash and PvP we could have the weight increase as the target's health decreased (since the more targets we kill early, the less damage we're taking). Then, amounts could be normalized so that the weighted and unweighted damage in each fight were the same. We could also have "weighted healing" and "weighted damage taken" modes, where the marginal value of health increased as the target neared death.