Ghostcrawler had an interesting post on critical hits today.
Back in Vanilla, the rule was that melee criticals did 200% damage, spell criticals did 150% damage, and damage/heal-over-time spells could not crit. But over time most of the DPS casters got talents or abilities that pushed their criticals to 200% damage. Pretty much the only people left at the 150% mark are healers and physical dps who get some damage from spells.
So GC is mulling over simplifying the entire thing with a rule that all crits do 200%.
Personally I think it's a good idea. It simplifies things immensely. Pretty much every DPS already has 200% crits on the majority of their damage.
As for healing, because damage crits do 200%, crit rating is expensive. So when you look at crit rating for healing it seems even more overpriced compared to the throughput it gives you. And then you add to that the fact that healers disdain crit because you can't count on it in the short term. At least bumping healing crits up to 200% would normalize the value of crit rating.
The one area of concern is PvP. A healing crit can be very swingy. Ghostcrawler suggests that the potency of the Mortal Strike debuff be increased to compensate. But then that can make having an MS class absolutely mandatory when fighting a healer.
I have a different solution. The "swingy-ness" of damage in PvP is mitigated by resilience. Perhaps we should use the same mechanic. Have resilience reduce incoming damage and also reduce incoming healing. So if you have a lot of resilience you're taking less damage, but you're also getting less healing. That will shift power away from the healers and make a random critical heal, even at 200%, much less of a game-winner.
Resilience would essentially slow the rate of change of your health bar in both directions. A lot of resilience would mean your health decreases slower, but it also increases slower while being healed.