Chiming in with the reduction of back-and-forth mess in ARR. HOW many times did we get made to run back and forth between Mor'Dona and Waking Sands for absolutely no reason, other than Minfilia/Alphinaud/etc calling us on the Linkpearl to tell us to come talk to them in person about stuff they totally could have just said over the linkpearl?

Protect was removed because the bosses had all been designed with the assumption that every party would always have it active, and like was already mentioned, this meant that any party without a WHM was taking lots of extra damage, because only WHM Protect worked vs magic damage. It was fun to slam that on everyone at the beginning, but it made WHM a mandatory class, and made SCH and AST the 'bad healer classes' which you really don't want to exist in an MMO.

I didn't play ARC/BRD during the 2.0 days, I was pretty solidly a WHM main, so I'm not certain what changes you're talking about there, but I'll join most of the other folks in saying that the subclass abilities were a huge pain. I hated having to level BLM to thirtysomething so I could get Quick Cast for my instant-rez. And like others have already said, NOT having instant-rez for the end content was unheard of for a healer, gating anything that powerful/mandatory behind 'optional' mechanics, makes it not optional at all.