My credentials to speak on this:
Joined WoW shortly after BGs were added. Started playing on World PvP server as an UD warrior who played fury spec. Shortly after BC was announced and my guild went poof I rolled a Tetra because I was tired of being cast aside because I wasnt the correct spec for my class. I have not had a similar issue up intill Cata
"oh and as opposed to rewriting these the examples will just be unaccredited to their original authors"
Remark type 1:
" Do you remember back then, when DPS had to CC, follow kill orders, not be stupid so the healer didn't oom? Do you remembering ooming before Cata?"
This is in fact untrue. I remember when I as a pally healer in BC and LK could have a pally tank run through 4 groups in a heroic and I could heal him all the way through no CC required. At this point AoE was required and blizz decided this was not a very good way to go about it and they changed this early on in LK.
-If you don't remember how it was or never healed back then please refrain from speaking the adults are talking.
Remark type 2:
"In other words, it's not that the content is too hard on healers. It's that the tanks aren't geared/specced right and using appropriate cool downs, the DPS isn't killing fast enough, mobs aren't being cc'd enough, and/or you are not using the most mana efficient heal spells (I'm looking at you flash heal) for the job."
The original poster here fails to see that not every mana problem across all healers is related to Flash heal and more to address his point I would like to say this: Making the game harder on DPS and tanks would mean we would see some sort of Aggro trend wouldn't we? currently we have the problem that some one runs out of health dies and no longer DPSes or tanks and the whole pull falls apart but if it was hard on everyone not just the healers then the case might be that the DPS must watch their aggro when going all out to try not to pull aggro? No blizzard in their cookie cutter wisdom has decided to make the ability of a tank to generate threat higher than the DPS when every one is pushing all the buttons in a mildly competent manner. So no DPS are not getting a challenge that was not seen in LK. Well what about tanks? how would one make the game harder on a tank? Well if a tank had to choose between mitigation and threat that would probably do it. Separation of the tanks abilities where when he protects himself he is not threatening at all ( as a man cowering behind a shield shouting insults would certainly fail to be in a real fight) or he is being very threatening but has left himself open to attack ( as a man doing a large amount of big hits would be making avenues of attack).