Tim:
Supposedly, it could show an ordinary user something they shouldn't know, hence the increased security, now.
Stephen Morris:
It depends on what environment you are in, if you are in an organisational environment then it is possible that it may show something that is sensitive (although I work in an environment where there are areas of the organisation that work with data they consider to be sensitive enough that even organisation admins shouldn't have visibility of it, only they should), but in a home environment that level of sensitivity doesn't really apply.
Upon reflection, I think it's more about limiting things that aren't really under your control (what some program can do behind the scenes). The user can always sudo to see that information, applications can't (not without your help).
Everywhere else applications are becoming more and more spyware in nature. At some stage they're going to try it on us, too. Better to nip it in the bud.
Look at web browsers, for instance. They spew out far more data about you than is necessary to do the job. Much of it is used to fingerprint and database you. That should have been nipped in the bud many years ago.