Its
more than a recognition, in my mind its also a
duty both to yourself and to the site. There is a certain prestige that comes with Citizenship and having the right to wear the badge and change the user title. People love that kind of stuff even more than they like getting new crowns for rep. With rights comes responsibility, in all aspects of life. You have the right to drive a car and the responsibility to do so in a manner that doesn't endanger others. You have the right to free speech and the responsibility to not infringe on others right to free speech. The list goes on.
With Citizenship you have the right to wear the badge, and the responsibility to act in manner that showcases why you got that badge in the first place. Citizens are supposed to be the elite of the site, the best contributors to the site in terms of user generated (as opposed to Staff generated) content.
And every single one of us should be expected to continue those contributions once we achieve the badge. But beyond that I believe that every single Citizen should be a role model for new members of the site. People should look at Citizens and say "I want to be like that" and not just for the badge. Call me idealistic I guess.