I'm sorry but You have more then enough force to throw heals and bubbles with proper use of Sacrifice. And there is more then enough time to switch between targets while being attacked. If you are being focused you are going to die anyways so why not give your teammate a bubble before going. You can kite and throw bubbles at same time. Can this always be done at all times no. But Seriously it isn't that difficult. How do you think healers do it when they get attacked. Basically you are the healer if there is no healer (unless of course you don't like winning)
And If you do have a healer and hes getting trained, its your responsibility to help keep him alive. If a tank puts guard on you it's your responsibility to help keep him up.
Sacrifice? The squishiest class in PvP is supposed to get rid of 50% HP points to gain some force in order to be able to cast a couple of heals on the next melee? And by doing so, he will make himself onehittable by every enemy melee? I must have missed the point where sorcerers were declared to be companions to friendly melees / training dummies for enemy melees.
Apart from that: No. It's not a DPS's sorc responsibility to keep melees alive. A DPS sorc has defensive CDs for himself, not for keeping melee gods alive. Use your own CDs.