In almost every instance of this trope more recent than Ralph 124C 41+, this is a sure sign that you live in a dystopia. It suggests a world in which human concerns are devalued, and society itself is engineered to make it easier for a large, impersonal bureaucracy to track and monitor its
Over the last few centuries, as Nation-States have arisen and consolidated their power, there has emerged a doctrine that everyone should have one and only one name, used in any and every context; that this is your only "real" name; and that the only possible reasons to use nicknames, pseudonyms, or any alternative to the name recorded in your governmental and financial records are to conceal unsavory practices, or perpetrate outright fraud.
A name that falls outside a limited range of acceptance criteria may not be accepted as a "real" name, and will certainly engender harsh feelings from governmental and corporate bureaucrats inconvenienced by the nonconformity.
As so many things have, this memetic push has accelerated across the close of the 20th Century and the dawn of the 21st.
Be advised, and be aware:
The intent is to make you easier to track. The intent is to make you a product.
Vernor Vinge warned us, thirty years ago: when someone knows your True Name, they have power over you.
Government watchlists aside, Google and Facebook aren't making money providing you with free email and search and "social networking". They're making money by selling your easily-monitored habits and interests to other corporations. If you operate under more than one name, if you compartmentalize your life and your purchasing power amongst multiple identities, you are diluting their product by making it more difficult to thoroughly profile you—and they consider that intolerable.
- EFF: Randi Zuckerberg Runs in the Wrong Direction on Pseudonymity Online
- BoingBoing: Google Plus's "Real Name" policy is abusive; Facebook is not a "Real Name" success story
- BoingBoing: Why are more people opting for legal name-changes than ever before?
- xkcd: Password Strength
- Addendum:Lauren Weinstein: The Coming Fascist Internet
(I have noticed, and not without irony, that the same kind of people who once ranted about Social Security Numbers as "the Mark of the Beast" tend to automatically and reflexively agree with the idea that people only have one "real name".)