I can pull like 4-6 mobs on the warrior and tank it for a while. But if I aoe with mages I either have to spend like 10 seconds+ with only warrior building threat before dealing damage at all or the mages will pull aggro and they die in less than 5 seconds if they pull aggro sometimes.
I also have a pala, so no instant shield to save the mage, flash of light is usually too little healing if the warrior has more than 2 mobs on it or if a mage gets aggro. So I have to holy light spam.

So if I try to AoE its not super effective because 1) warrior has to spend alot of time building threat 2) healer might go oom if warrior takes too heavy dmg over too long time 3) if mages get aggro its best case 1 ress after pull, worst case a wipe.
If I sheep as many as I can while frostbolting 1 by 1 target it works okay, but its quite slow. each mob dies after ~4 (x3) frostbolts. so its 10 seconds per mob, instead of like 10 seconds per 4-6 mobs or more if AoE'ing.

It feels like if I had a prot pala instead of prot warr life would be alot easier. Or if I had your setup with more aoe dmg and healing, since that has obviously worked very well for you.
It seems I have done the mistake of landing somewhere in between 2 decent setups. I am unable to use my mages aoe effeciently because the warrior is holding me back, and I am also not optimized for killing stuff 1 by 1 like a warrior cleave because the mages need to drink alot.

In SM I could pull 10-13 mobs at a time and tank them all with demo shout spam, so the current situation is really alot of steps back.