Like he said, nothing much wrong with it... just a nusance more then anything (the micro bubble kind anyhow).
Unfortunatly, bubbling air on purpose doesn't do too much for the water as far as injecting oxygen. The nature of saltwater tends to keep more oxigenation out (due to, I've always assumed, the highr specific gravity).
If you are interested in boosting the oxygen level of your water, try an ozone reactor.
But as with any sort of addition, do read up on the pros and cons and don't jump into anything.
One of the big reasons of the limitation of fish in a marine tank is the dissolved oxygen, but there are limitations to everything.
They probably love it because it is activity they can see and go after it hoping for food... either that or they are bored
I have a spray bar slightly at water level on one end of the bars...it produces fine bubbles from time to time depending on the wave maker... they go after the bubbles if they see em...like a cat after a sparkly I spose..