It was a problem under XP too. You created a limited account, and it
turned out that you were unable to start certain programs. So you
thought that limited accounts were worthless. I have been using XP
with an administrator account for years, and I have only recently
discovered how to use XP with a limited account, which is so much
safer.
Vista is worse.
Some programs, such as Agent (which I am using right now to enter a
message in the newsgroup) even cannot be started if you log on as
Admin. Of course you made sure that you had access rights to the Agent
files. But the program crashes immediately, without error message, and
you have no idea why.
Agent can be started (under any user account) by right clicking on it,
and selecting 'Run as Administrator'.
I do not believe Microsoft intended this.