Unfortunately, I doubt you'll find an in-universe explanation. The only answer I can think of (and @Kevin has also expressed) is that it would have been very difficult for the writers of the mid-late '60s to have imagined the technology that we have today. Even in the late '80s to early '90s, when STNG was in production, hand-held Personal Access Data Display devices similar to the tablets (Does anyone else think it's not a coincidence that one is called the i*Pad*?) we have today were science fiction fantasies.
I believe it is much easier for us to imagine things for which we have little or no comparable analogue in reality. Faster-than-light travel and teleportation are two good examples you've given. However, consider what the state of computing technology was in the mid-late sixties. Computers were still far from commonplace, and not at all accessible to the common home. Even the most modern machines were still as big as a minivan or larger, and mass storage units were the size of refrigerators. The few cell phones that existed at the time had to be supported by suitcase-sized base stations. So, imagine traveling back to that time and convincing someone there that some day you'd be able to carry a minivan, refrigerator, and a suitcase all in the palm of your hand!
The science fiction TV writers of the '60s could hardly have imagined that we would eventually have hand-held devices that have so much more capability, power, and storage - let alone that it would be achieved in just a matter of decades. Even in the '80s, Orson Scott Card was far ahead of his time when he wrote about things like advanced hand-held gaming devices, hand-held computers, a world-wide computer network, and social media.
In making a prequel to a work of futuristic science fiction, especially when it's being made decades after the original, and especially after the technological revolution we've been in during that time, it's inevitable that some things in the prequel are going to be incongruous to existing canon. Despite the obvious conflicts this would create, the purpose of this is still for believability.
In the 1960's it was very believable that the people of the future would still be working largely with paper documents. Today, it would be absolutely ridiculous to propose such a thing. The writers of Enterprise simply had to make some adjustments to suit a more modern audience.