The amount of bandwidth that people are using is increasing dramatically. So they can either encourage people to limit their traffic, or charge an even higher amount for a truly unlimited price.
95% of their customers don't even come close to 250 gigs, so would you rather they raised the 'all you can eat' price for 100% of their customers or just charge extra to the 5% who use a lot?
I have no idea how much I use in a month. Nor do I want to start tracking it. I'd have to measure not only my web browsing, but file downloads, connecting to the office VPN, Skype, and all the other stuff that I do. Not to mention whatever the Xbox uses for online multiplayer - not even sure how I'd be able to measure that. But whether it would all put me over the limit in any given month or not is beside the point, which is that I'm not interested in a limit in the first place. As I said, pay-per-kilobyte died in the 80's and it needs to stay dead.
95% of their customers don't even come close to 250 gigs, so would you rather they raised the 'all you can eat' price for 100% of their customers or just charge extra to the 5% who use a lot?
I'd rather they stop broadcasting basic cable channels via analog. That'd free up gigabytes of bandwidth. Otherwise, they should keep delivering the service as they've already agreed to deliver it. If they need to raise the price, so be it. Raising the price will cause me to shop around. But charging per KB will cause me to cancel Comcast immediately and permanently. So it's up to them.