Are the witnesses the only religion making this push to digital?
I can't think of anyone else who badgers their flock to abandon print.
As far as I know, yes. I've never heard of this and I really don't understand the point of making people feel uncomfortable (and "unspiritual") about using print books and a hard-copy Bible. Other churches allow both and it would never be mentioned as an issue or measure of devotion to God. I'm not an oldie but I still like print books. There is still tremendous value in print. Just like Lieu mentioned, it's portable and not dependent on external conditions. With the Bible, sometimes it's much easier to go to multiple passages in a hard copy than waiting for your phone to load on slow wi-fi.
This is a case of the Watchtower not wanting to spend the money. Because they are the only supplier of these materials, they are the only one bearing the cost of publication--and they don't wanna. It's also much easier to alter and remove digital media. Huge benefit for a group that would rather not be reminded of its past or keep a paper trail of its inconsistencies.