I don't think it was intended to be a social experiment.  What it was supposed to be is upholding equal rights of the citizens.  Having served in the USAF, there are plenty of places where a transgendered person could serve effectively.  And, I can cite many, many instances where idiots were allowed not only to serve, but advance to positions of authority only because they could test and fit the system, which are the ones we should be trying to exclude.  Of course if we got a bunch of smart people in the military, they might expose the wars for the train wreck they are.