To 'express yourself' you should use the personal message, not your display name.
Other than that I agree with you that removing the possebility to have a display name other than your real name in Messenger (without changing your real name in your profile) is one of the worst decisions they've made.
The official reason behind it is so all the social network (namely Facebook) can now be syncronized better and the names you have across the Windows Live services and other social networks are the same. All in the name of 'to keep things the same/simple'; to make it more easier for the user to manage all the names, so to speak. But instead of fixing the issues on the Windows Live platform regarding different names across the different Windows Live services, they simply decided to remove display names all together and assumed everybody would like everyone else to see their real name.
See:
http://www.liveside.net/main/archive/2010/06/19/w...es-to-go-away.aspx
http://windowsteamblog.com/windows_live/b/windows...-your-privacy.aspx
topic: 'Additional privacy and profile changes'
Another argument of theirs is that people would better be recognized when you use their real name. Well newsflash for them: on the internet it is certainly not uncommon to only know a person by his or her handle/nickname and not by their real name!
It speaks for its own that not everybody agrees with these reasons and that their explaination is pretty poor. If you look at the demographics and stats of Messenger, Facebook and other social networks, together with how privacy is percieved around the world, then it is pretty obvious where such a decision comes from imho.
In the US, almost everybody uses Facebook (it is also the most used social network there). There it is also not uncommon to use your real name instead of a nickname and it is not seen as something strange to use your account both for pleasure as for business.
However, in the rest of the world, this is quite different. For instance in Europe, they are a bit more concerned and picky about privacy for instance; A name is seen here more as a private piece of information. And Facebook is not as widespread and using different accounts for pleasure and work is done more frequently.
But a 'problem' with that is that Facebook is designed around the fact that people should use their real name. It is actually against their policy to make a fake account (read: use a fake name) or make more than one account.
Putting all these things together and one can see where such a decision realy comes from and how they seriously made the wrong assumptions, probably governemented by their own social uses and views. But doing something like that for a program which is meant to be used around the globe is in my opinion, stupid and very shortsighted.
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