i read a marketing paper on this in school, cant remember who did it.
but his thought was that it would cut down junk mail in the long run. it would be more direct marketing, cause of users being identified, and they could be singled out for special deals
the tough part is it may give out a lot of info on you, there is so much tracked via the net, its a tough line to draw
i think with the generational struggle right now, we wont see it for a little while now. the older seem to be fighting to turn it back to the '50s and the younger want to move on (a sterotype i know, but from the people i am around, this seems to be prety consitent)
change scares to many people