That's kind of a disingenuous statement. Paladin healers are arguably less vulnerable to stuns than other healers because they can get out of one with Divine Shield. The only other healer abilities that can be used while stunned are Barkskin and glyphed Pain Suppression.
I totally disagree. Back when we had sacred shield maybe that was the case, but not since we lost it. DS is on a really long cd. Druids have barkskin on a short cd and hots. Priests have shields and ps. Shaman have earth shield and as you pointed out, grounding totem. If a pally is stunned they take full damage. A pally must pray that they survive the cc and try to get their health back up asap once they are out of it. CC sucks for all healers, but I do feel pallies are a bit more vulnerable. Though probably not by much.
Shamans also have three instant cast heals. Riptide, Unleash Life and that talented instant heal they get when they dispel stuff. Perhaps none of these are as good as WoG, but WoG takes 3 hp to really shine. And as I said before, HS was nerfed very badly on the beta. I don't think shamans are in a bad place in pvp right now. Maybe they need a bit of tweaking. Priests, on the other hand, do need some serious help in pvp.