hm.. theres not a real solution for solving trolls only, or pirates only or any of that sort
like kryo said, once privacy is gone its gone, and surely peoplewill try to "improve" the rule for their need, more tracking and being able to see and thus control what is going on,
as soon as some "popular"guy is constnatly nagging you on a forum where everyone is behind him (friends) you'll just think... w/e fuck the guy ima move on (on most occasions anyways)
having this number stuck to you forever will not do much good
tiny example is a minigame of warcraft III called Battleships, game creator = a totall ass (in my vieuw) since he banned my name from his game there, reason? i aproached him of his manner on his quotes to the losing team or people that quit the game (multiple reasons possible),(ima not repeat that sentence here, wont do me and... err.,.... .. yah. wont do me much good on the "never swears" list)
anyways, he banned me for that, and if i should have an ID number attached ima guess he wouldve banned that one aswell... atleast now i can just make another name and play his games anyways (cuase even tough i dont like him, his game = great)
and yeah, the id nubmer in question should ofcourse.. not be public but you'll always have people that find a way in.
thing that makes internet great = anonymity on the internet you can talk whats in your mind without major consequence, you'll find people whom totally agree with you, and people who are totally opposite, and ofocurse the local jerk/troll but you'll ignore those or start making fun of them
in real-life everyone knows your face, so you cant rlly talk with the words your having in mind.... and you'll always find some "weird" guys that aproach you and start doing dumb things (real life trolls???) but you'll just ignore those 2 (best and prolly only thing to do..for your own health)
so that short, internet a place where peopel can express opininos without fysical consequence, adding an i-d tag to someone will take that away, and ofcourse theres peopel who'll abuse it by placing quotes that are just mean, but like trolls.. you ignore them