Unfortunately, it's pretty hard to get all the security benefits of modern technology without the distraction, the sloppy user interface, the complexity (and attack surface) and user hostility -- in a word, without the incredibly poor design -- of modern technology.

A pager-like device with proper encryption isn't extraordinarily challenging. But planned obsolescence or selling ads is pretty hard to do with this sort of technology, so despite plenty of interest from users, there's not that much interest from companies.