To be really honest, block can be removed, change skills that have effect on block rate to parry and it won't affect PLD that much. The 3 types of shield thingy is pretty poor of a concept in the first place. RNG defensive stats is IMO worst in games like FFXIV where your active CDs are your bread and butter. The real thing that it is RNG means that there is no telling which one it will have effect on whatever attacks, Sheltron being the bypass but for the most part, you just don't rely on block/parry to do their job to survive.

If SE wants block/parry to be relevant in the real future, those stats need to be significantly better by at least x2~3 the reliability (the strength of block/parry will need to be lowered if that ever happens). Unlike traditional MMOs, tanks in FFXIV not only take auto attacks, they also play around timed tank busters. Also, another point is how the whole stats are working in the game. Parry/block comparitively are about the same value as other traditional MMOs, the break point being parry/block are constantly compared to offensive stats like crit/det that actually offer better returns.