Folks have lost clearances and jobs. I don't know about prison time. But I do know the fear of these things happening is a motivating factor not to cross the line. But I'm just some guy...
The cases of caught individuals seem to have gone under-punished, as they sound worthy of prison time.
Also, even if the NSA polices against personal abuses, why would it police against systematic abuse for government's purposes against the constitution?
Self-policing does not work well, especially without elaborate mechanisms to enable it to work, and especially with a combination of secrecy and lack of oversight.
Now, systemic problems are a different issue. But the article we're all talking about here is written by an analyst from his own perspective.