Taking away spell pushback on smite would make doing dailies as holy 1000x less annoying. I don't expect to be able to grind super effectively, but that one little change would make doing dailies so much more bearable for me.

Put shields up between engaging mobs. If you're taking them on one at a time they'll almost never break through your shield before you kill them.

I was thinking more along the lines of "let's spice it up a bit to attract people/make people stay".

What got me thinking was maelstrom weapon and the way enhancement shamans can toss out some healing. What's stopping Blizzard from making an equivalent mechanic for "Cast X amount of healing spells, get an off the gcd instant nuke". Another alternative would be to make critical heals deal 30% of the damage not overhealed to the targets' target (I.e. healing the tank does damage to the mob being tanked) for zero threat.

Shamans getting free mana cost earthshocks/flameshocks if riptide is on CD, druids proccing instant startfires for zero mana if their target has three stacks of lifebloom etcetera.

As a tank, I'm finally feeling like I'm fighting against an enemy, not simply against my own group composition or to only protect my partymembers. I'm sure a lot of healing specced players would appreciate something similar.