I don't really get the headband thing. It's one of those things, if you notice it, then it's an eyesore, but if you don't, then you don't.
Like I'm sitting here watching OKC vs Lakers game right now and I've only noticed that Carmelo is the only player wearing a headband. I hadn't noticed it until I opened and read this thread.. LOL ..
If it makes a player play better (less sweat dripping on your face, etc), then they should be able to wear it.