I've been playing a lock since beta, and it use to be the reason we had such high health pools compared to other casters was because we needed to life tap for our mana, and mages typically had higher dps to offset this class perk.
Since they normalized caster equipment, we have kept our larger health pools and while im certainly not complaining at the extra health, I wonder if we are still being balanced upon this supposition. I think i would prefer a higher balanced dps to lose a bit of health.
Granted it was fun last night when i said 'hey tank, look at my health (which was at 776k due to the sacced voidwalker ability). The tank was only around 540k.
even without the ability going im running raids at 519k or so. everyone else is around 375k.