You may or may not be surprised that many tools needed to provide an "email only" service already exist and are quite easy to implement.
Something as easy as allowing email + 3-4 links past email would solve virtually all problems and support calls and a bit of usage monitoring would eliminate the fraud
Tell me again how charging by amount of data use and speed is not already solving this problem? I can go to comcast.com and buy an email only package right now. Also, why is this suddenly going to allow you to take market share from Comcast? Do you honestly think the reason we don't have competition in the ISP space is due to not being able to unbundle packages?
Something as easy as allowing email + 3-4 links past email would solve virtually all problems and support calls and a bit of usage monitoring would eliminate the fraud