We never heard the contents of the missing teenager's voicemails, simply that it had been hacked. The fact that we are hearing the contents of the Royals voicemails is very significant in itself.
To be honest, I think these were probably the least embarassing or intimate ones and I believe William and Harry must have given permission for their contents to be read in open court. Ginger! Babykins! Knowing that these were intercepted lets us know that there were plenty more where they came from and that if they could hack them they could hack the Prince of Wales, the Duchess of Cornwall, the Yorks, the Wessex's, the Prime Minister's! I am sure that if HM had one it would have been toast too.
The degree of embarassment coupled with outrage that people feel when hearing these voicemails is racheted up when it's people who are vulnerable to having their initmate personal details made public or sensitive information that would never, ever become public knowledge. It's the unknown that is the worst. What information may they have left that could have resulted in dangerous consequences for the unsuspecting victims?
It's not just a moral outrage, but a security nightmare!