Our software is used from portable devices (usually usb) as users move between computers (PortableApps.com). As such, using bittorrent would be a technical option within our platform's app store/updater. It would, however, get our platform banned/blocked at many companies and universities that have policies forbidding bittorrent use. (And we can say all day long that it's a legit protocol with lots of legit uses like downloading linux ISOs, it doesn't change the facts and policies on the ground.) Additionally, most users will be behind NATs that they can't poke a hole through to be able to properly share.

As for images, the bittorrent protocol would just be way too slow even with some changes when compared to HTTP with SPDY and all the internal tweaks done at the geographically close CDN edge nodes to make them as fast as possible. 150ms before adding a new peer is an eternity in an age when 47% of people expect a web page to load in 2 seconds or less and the abandon rate increases with each second that passes with 40% abandoning at a little after the 3 second mark.