While I like what Jimbo said, and what he agreed w Tony Sidaway regarding, I should hope he doesn't agree w tony on the following:
One pretty good way to find out would be to take away the user categories and see how many people leave. If they mostly stay, we've gotten rid of things that facilitate the abuse of Wikipedia. If they mostly leave, we've unshipped people who were here for the wrong reasons. Either way is a win.
This is not only completely illogical, it underscores how out of touch admins can get. Intentionally taking away a source of joy from large numbers of users in a bid to see if they'll leave, or if they'll just accept your hegemony over them... thats pretty much the opposite of my recipe for success in a volunteer setting.
Sam Spade