I guess it depends on one's social circle, but where I hang out -- mostly among the journal roleplay crowd -- "Please don't take this icon" on the allpics page is often regarded as an invitation to take the icon because clearly you're 'stuck-up' for not wanting to share it with the world. Of course this behavior is already possible on DW, but I'd hate to see it made even easier. (Maybe the real solution here is actually customizable privacy on one's /icons page...)