It's still not a good idea to throw fire around if you aren't immune to fire. He shot continuous streams of fire directly from his hands, and even short streams of fire would sear your hands badly enough to warrant a trip to the ER.
Also there's the idea of super-strength without the super-durability to go with it. Pick up anything that your skeletal structure can't support and that's the end of your arms.
And in terms of uselessness, there's always the power of Heart. Poor Ma-Ti got 5th billing to Wheeler because of his "power."
But to take your power a step further, to cause all organic matter within a mile of you to become poisonous and die. So you'd kill everything and everyone you ever knew and loved, and destroy or poison anything you could possibly eat or drink.