The history of the QR code goes back to when internet connectivity could not be assured. I remember being in PVG (Shanghai) and I would tip the girl at the noodle shop in the terminal to get the response to the WiFi sign in with her Chinese telephone number so that I could get on the internet. Without an internet connection, the only way to get the route into Jepp FD without internet connectivity was to type it in. The QR code was a quick way of getting the route from the paper flight plan into the tablet. We were using the Surface and Jeppesen even incorporated a QR reader in the Windows version of Jepp FD.
We now have cellular iPads with worldwide coverage, so the QR code is no longer needed. However, the way the QR code works on the iPad is that it is just a URL. The URL scheme supports the QR code, but more importantly, it supports creating a link in the flight plan to open the e-mail. Much to my disappointment and frustration, Jeppesen created this requirement for the digital signature in each link. I hope that Jeppesen eventually eliminates the requirement for the electronic signature.