I do like it for the minor DPS bump and significant TP recovery with Bulwark, but I agree that giving it an Enmity bonus would be quite welcome. I don't think there's any need to remove it from the GCD, especially since it doesn't break your combo.

As for Flash, you can't use it as often as you can use Shield Swipe (since you'd just run out of MP), it does no damage while still using a GCD, and in some fights that MP is better spent on Stoneskin. So it's definitely only sometimes an improvement over Shield Swipe.

As for giving PLD more off-GCD offensive abilities, I agree that one or two more would be quite welcome.