You know the range of the stun is only 5m right? So once you realise the other team as a stun bubble healer just try more than 5m away when it pops. Every single melee dps class has abilities that hit at least to 10m (whether as part of their main rotation or not) and thus can avoid it.
I prefer staying full healer spec on my sage as, like all the other sage/sorcs have said you sacrifice too much healing for a (mostly annoying, but not useful) gain in utility.