you answered it yourself, sexy looking makes sex better, it's a visual/mental thing for me anyways, I don't think the actual sex itself is any different pierced or not ( from a guy with a pierced girl perspective )
The best BJ I ever got was from a girl with a pierced tongue. I used to make her take it out, and it just wasn't the same. I'm now with a girl that doesn't have one, and I sometimes have to look down just to make sure that I really am getting my dick sucked!
I don't know if it necessarily made it better. At times it was almost too much sensation, if you know what I mean. The bad thing is that I got used to it, and now I have to go back to the old way. I suppose, if you never experienced it, you wouldn't know the difference.