I believe it was intended to be a TP throttler in that you don't burn as much TP when using it.

It should remain on the GCD to serve that purpose but it should also have its threat significantly increased so it is no longer a net threat loss.

Is this game-breaking? No. Are PLD fine without such a change? Yes. Would it be nice? Yes.

The devs have more important things to worry about than to adjust a class which is perfectly fine as is right now.