i believe some LFS use them to help the fish breath better under stress since the little guys been through hell and back when swooped up from the ocean, bagged, transported, put in holding tanks, then bagged again, then transported all around the world to LFS, and then back into a tank. as you can see this process sounds pretty hectic. When fish are stressed they tend to breath heavily so the air stones and bubblers help oxygenate the water more.
I recommend having one on stand by for when you have to do any kind of transportation of the fish from one tank to another. this will help keep the stress down.
but i wouldnt use one in your main tank since your skimmer kinda does the same thing. plus you dont want annoying micro bubbles every where in your aquarium.