From Yoshida himself

[ErikMynhier]

There can be no content that requires a WHM to complete. Let that sink in. There can be NO CONTENT WHATSOEVER that can't be completed with an AST/SCH. Given that fact (and it IS a fact), why bring a WHM when you can bring an AST (20% more damage to the group) and a SCH (20% more crit to the group vs the boss)?

Idk man. I don't really care either. End of the day its the player. BiS class can be garbage in the wrong hands. So who cares.