It may of sounded good on paper but it not working for the masses.
Its a simple fix, just lock out all abilities when you hold block kind of how sprint was before this update when you couldn't use abilities when sprinting, this will keep pve tanks safe while also lower the effectiveness of pvp block casters and making the combat more strategic both from the player blocking and attackers point of view.
This will make it so that both the attacker and player need to think before striking or casting abilities, this will also give attackers a tell sign as to when attack a shield user and the player using block a risk vs reward system when using a shield.