I'm typing this as a raid, so run-on sentences ought to be excused.
I am crossing my fingers that, come Cata time, healing will be a game much more about mana management than time management. I remember the days on the "FSR Shuffle" (when you would actually stop casting for, say, 30 secs at a time to regenerate mana) because... wait for it... you didn't have bottomless pools of casting-juice!
Lemme break it down (LL Cool-J style, if I might). There are two factors that make the healing game: time and mana.
Time is, the amount of time you are given to heal the incoming damage. Too little time, and healing can become frantic and the raid will die because, welp there just weren't enough GCD's to get the job done.
Mana is the amount of resources you are allotted to get the job done. If you could cast endlessly (think most of WoTLK raids), you would just cast your fastest/best heal all the time. That's why Druids are Rejuv bots, Shammies are CH bots, and Discs are bubble bots.
How 'bout an example, Epicmedic (me)?
Say a 25-man raid has 6 healers. Say we 6 have 30,000 DPS tat must be healed, with spike damage on tanks. Assume the Pallies and Priests take care of the tanks and the Druids and Shammies toss their AoE's and HoT's and we can manage, with no mana issues.
Now say that same group only has 15,000 DPS to heal through. Pretty boring, eh? Not if mana is an issue. See, if healing spells were more expensive, the Shammy would have to consider, may actually have to use his brain before throwing a Chain Heal on everyone that sneezes.
Oh, and bonus! It's less stressful. Healing can feel like a job - it's fucking stressful when anyone, for any reason, at any time, can go from 30,000 HP to DEAD in less than a GCD. It makes my wrist hurt, too.
Now, for most of Wrath of the Lich King, time has been much more an issue than mana. And Blizzard has stated repeatedly that they want to make healing more dynamic, more responsive, and require more thought, than just spamming whatever is your best spell over and over (and ovvverrr).
Here's to balance!
