Communication in Rogue One isn’t instantaneous enough to call off the rebel attack on the weapons facility in time. There could be a delay of several minutes between receipt and reply. In the real world, there was a delay of a couple seconds between Earth and Apollo crews on the Moon.

Krennic was trying to plead his case in person, (going over Tarkin’s head) something that would be less effective otherwise. There’s also the possibility that Imperial officers spy on each other and eavesdrop on communications, making it more imperative that he have a private audience with Vader.

If anything, communications are too sophisticated in the prequels. We only saw one case of a long distance hologram call in the OT. And such communication probably requires a lot of power.