"I don't want to think while I play, so no one should be allowed to."

[LittleImp]

Everyone else: Okay, so shields fall off near-instantly, yet they negate damage all the same, if you have time to DPS you have time to reapply a shield to the tank who is always getting hit, especially when he has no more CD's to burn.
"I don't have anything to do."
Everyone else: Did you not just hear what I said?
"I can do DPS instead"
Everyone else: The tank might be more appreciative of not having to be healed if you keep the shield up, especially during big pulls.

This is just objectively bad. Please, NEVER EVER play like this. Dealing damage and killing mobs faster is a significantly more effective form of mitigation than spamming garbage GCD shields in combat.