Thing about it is; if they do that, you see more Tanks in arenas then, which IMO no tank should ever be able to que into arenas. It should not even be an option for that type of play, however, if they made it so no tank can que into arenas, then by all means yeah def make tanks very fun and awesome in PvP/around PvP RBG designs.
Guardian is much tankier than VDH, but VDH has more mobility, mainly because Guardians do not shift out of bear form while under attack. They can travel form while not being attacked, but the moment any kind of PvP combat is coming up they need to stay in bear form, otherwise they have no armor and no extra health or anything.
Blow for blow, though, Guardians are much tankier than DHs, but they just can’t move well.
What makes Prot Pallies bad as FCs is that they have no HP for the burst windows that most specs have, especially melee and Boomkins. Same with Warriors and Monks, though Monks got stagger, which they can stagger Magic damage with a certain talent.
Nonetheless, though, the toolkit the Paladins have for their spec works for PvE, but not for carrying flags. Warrior’s toolkit is fine for FCing, but, they just got no HP to stay alive with. The Druid’s entire niche, for the most part, is having the ability to travel fast in outdoorsy areas, but also more than that it’s in their healthpool size. My bear’s only 205, and I got like 55k hp in bear form.
I wish you could Taunt players and force them to attack you in PvP, but, that’s not a thing. There is a PvP talent that let’s you taunt players, but, it just increases the damage they take rather than forcing the player into attacking you instead like it does in PvE.