The fact remains that without us, there are very few mechanics that can cut off a Resto Druid's heals so they can be DPS'd down. For all the other classes, PvP healing is OP enough that you don't need your extra buffs to produce decent heals, and you shouldn't be able to remain alive indefinitely. It appears that this is what healers, when we get down to the truth of it, want. They want to be invincible, to just have to stand still and heal through anything a DPS throws at them.
IMO, there used to be a rough formula that was observable in PvP:
A DPS could always take out a healer, 1v1.
A tank could always endure a DPS and wear them down, 1v1.
A healer could always heal through tank damage without going OOM, 1v1.
IMO, this was a fair and equitable system to work with. But I'm getting a little off-topic, the point I meant to get at was that Purge, particularly with the glyph, is supposed to level the playing field, or even give the shaman an advantage. We don't have debuffs, not in any real sense when compared to the diseases of DKs, or the curses of Warlocks, etc. Our mechanic is to take what makes you stronger, not add something to make you weaker.
... And no class, besides perhaps Rogues, has any right to complain to a Shaman about survivability. None whatsoever.