The point is that in Cata your entire healing rotation is fundamentally changed. For example, Im a resto druid, before I used to blanket everything with rejuve, lifebloom (now only able on 1 target) and the occasional wild growth. Now, I have to spam Nourish since its my only cheap spell, and be VERY carefull with rejuve since its insanely expensive atm.
So all I do now is very carefully apply rejuve and lifebloom on tank, keep lifebloom up and refreshed by using nourish. When clearcast procs, I use regrowth for freebies. Once I break the 100k mana barrier I will be able to use rejuve more liberally, till then, its just casting slow sluggish low-healing spells (nourish) simply because its the only way to manage mana-output.
This saved me at least 80% mana compared to my old healing method, which I tried for a while because I was to stubborn. After each pack I was oom, with a mana pool of 70k mana. After my drastic change to cata-style healing, I rarely ever run oom and drink occasionally instead of compulsively. Its a big step, ill admit it, especially for druids/shamans and perhaps priests (not sure, never played priest) but once you get the hang of it, its actually much more fun because of the triage you have to apply and the challenge it offers!
Plus, you must not always blame yourself, you can actually blame the retard dps in your party/raid that is standing in the fire. Most dps is fairly clueless on what tactics to do since only tanks and healers are bothered to read up on tactics for the new encounters. They expect the tank to keep aggro and healer to keep em alive. Dont be frustrated when confronted with such incompetence, just let them bleed and die
Repair cost will force them to actually wake the fuck up, works like a charm. Thats what I call triage.
Wotlk was merely a setback.