That's hardly something new and specific to the 5.0 at all, it was like that in 4.x too. That's what you get when you put the "healer must dps" mentality so well into the players heads that they come to the point of not caring of their primary role anymore.

Before the aggro changes it was like that for numerous tanks i did stumble upon too. Not wanting to use the tank stance and the aggro combo because of the dps loss, and losing aggro even though i did use lucid dreaming and diversion correctly.

Maybe in 6.0 all healers will be changed into some sort of "you now heal and shield group members for a part of the damages you inflict on the ennemies" wow disc priest, so that they can fully concentrate on their dps rotation like the tanks we have now XD