Another vote for "living in an area where English language books are difficult and/or expensive to get." I used to go nuts in the bookstores when I was visiting back in the US and haul home a suitcase packed with books (and other goodies) a couple of times a year.
I'm now not going back to the US as often, and with the luggage restrictions getting tighter, figured why load up on books I have no room to store any more? Didn't need the temptation to impulse buy via 3G, nor the distraction of wifi - and honestly, I'm fairly serious about reading what I want to read by getting around the geo restrictions however I can.
So I ultimately went with a Sony and Calibre to download the newspapers and magazines I'd normally read online.