Name one other utility you get unlimited use of. Cable/Satellite TV is the only one. Yes, TWCs plan was ludicrous, limits too low and prices too high, but we all know bandwidth costs (initial network install, electricity, salaries of people to keep it running) and its NOT fair that Grandma and Grandpa pay the same $50 a month as little Johhny the BitTorrent master down the street.
Paying for speed is a gimmick, we should be paying based off what we use. I barely download, a per GB plan would likely save me money in the long run. I dont think it should be $X for 30, 60, or 100GB, it should be a flat per GB charge, and whatever you use that month, you pay for. If I go on vacation for a month and turn all my PCs off, I should have a $0 bill that month. If I go nuts and buy 10 movies, I should expect it to be a bit higher.