Certain abilities should be off the GCD

[Jahaudant]

I see it as more of a active tool than a reactive one to be spamming to stop every single skill attack.

You can spam shield bash right now as much as you want. If it was off GCD and given its own cooldown (say 30 seconds) the skill itself becomes far more of a commodity in that a great tank will learn exactly what they need to use it on and when. This adds depth IMO.