Courtesy of Susan Crawford:
Non-neutrality ... serves the interests of those who would like (more generally) to see the internet morphed into something much more akin to the current wireless model here in the US: a fully-monetized network, permitting use of particular applications that share their revenues with the network access provider. (This network would not be the same thing as the internet.)
It takes a lot of work to change an open system [like the Internet] into a cellphone system. But a cellphone system would put the network operators (and their friends in Hollywood, and law enforcement), back in charge of communications. They'd be able to charge whatever they want, outlaw whatever they want (eg, unwanted P2P communications, non-CALEA-compliant communications), and generally run the show they way they used to in the old days.