Just take it. It's a good thing to have. It shows the employer you tested at a higher standard than needed to and passed at a national level. Why people chose to discourage things that only improve the system or themselves, is beyond me.
Same goes with the "degree" programs. Sure, taking a literature course, a psychology, or some random computer skills class probably does not make you a better paramedic, it DOES prove to yourself you can accomplish it. It shows you want to be educated and not fast track your way into the field. Makes you a more well rounded person that has the ambition to learn.