Quelling strikes isn't really a free pass to go all out. You are right about BLM and BRDs in particular as they are the classes without "ramp up", while melee can do overall more dps, BLM+BRD can frontend a bit more. I think many don't really understand how quelling strikes works and how far just looking that the enemy list and attacking the damaged ones first can go. Of course, popping quelling strikes and going all out on a mob the tank isn't focusing on is still going to get that dps aggro. It's not really the tank as it is the dps's lack of paying attention to what is being damaged (that is what the enemy list is for).

As far as tanking groups of mobs, don't forget about using a riot blade combo to regain MP so you can keep up flashing. Sadly as you said, as far as AoE tanking, paladins are "flash beacons" Doing a rage of halone combo on a single mob just means you will lose threat on the others. You could always mark attack targets, but I think we both realize that doesn't often work in pugs where people just do what they want and don't pay attention.