They want to monitor what you bring through that bandwidth (remember: that you're already paying for!) and charge content providers more based on that information.
This is bad. This is bad bad bad bad bad bad BAD.
Take this scenario as an example:
Comcast (or any cable provider, really, but here I'll be using the broadband equivalent of Beelzebub himself) notices that a lot of their users are streaming Netflix. They call Netflix and say,
COMCAST: "Hey, you're slowing down the traffic for our users; we need some more money from you. Like right the hell now."
NETFLIX: "Uh, no."
COMCAST: "Well, if you insist." /Throttles all bandwidth from Netflix servers to a crawl for all of their users/
NETFLIX VIEWERS ON COMCAST: "OMGWTFBBQ I CAN'T WATCH ORANGE IS THE NEW BLACK NOW I'M GOING TO HULU PLUS INSTEAD".
NETFLIX: "Wait! Come back!" /Turns to Comcast/ "Fine, take your blood money, Faust."
COMCAST: /Cackles madly as lightning flashes in the background/
NETFLIX: "Well, now our profits are going down. Can't have that." /Raises the monthly rate for all their viewers/
NETFLIX VIEWERS ON COMCAST: /IMPOTENT RAAAAAGE/
We can't let this happen! But the good news is, we can still do something about it!!
Contact your representatives. Let your voice be heard.
It's your internet- fight for it!!