The main problem with quantum encryption is that it requires special equipment for all parties involved, while standard encryption can be done on any regular computer. The more you spread it's use in a large bureaucracy, the more chance you have of someone, somewhere doing it wrong and leaking critical information by not following the proper safety protocols.
Last time I checked, QE was used only for key exchange, not entire messages. So if you can manage to acquire a key, you're good to go. Personally, I wouldn't even bother, there's a lot more chance that any number of highly classified documents can be found unencrypted on employee laptops, in temporary files or by checking the swap file.
Some of the most successful hackers get their information using "social hacking" where they phone humans and pass themselves off as tech support, IT security, etc. While QE is in itself perfectly secure, the surrounding process and especially the people using it, are not.
Do they touch on elliptic curve cryptography? AFAIK, it's currently the strongest non-quantum system we have, allowing much shorter key lengths to be used.