My 83 year old mother had no problems learning to use a PRS 650. When I showed her mine, she immediately dived in to a book. With a quick demo on how to change the font size and turn a page, she was set. I loaded her's with a bunch of free promotional books that I already had downloaded and some classics that I knew she would like. It took a few demonstrations on how to check out library books and she was all set. Her biggest problem so far has been remembering how to charge it.
I don't think that the technologically averse find it any harder to download on to a computer than they do to navigate to a bookstore to download books. If they mostly want library books, as my mother did, I don't see any advantage to WiFi in a reader.