The only reason they are making any changes is because the FCC is considering doing something.
As a point for comparison where I live there are two cable providers, Cox and Comcast, covering different parts of the city. Cox has a data cap, but it is 2TB. Also that is a soft cap. If you hit it, nothing happens. They may call and complain at you if you do it too much, but that's all. It is there to try and keep people reasonable, and so they can cut off someone in truly egregious cases (I've never actually heard of anyone getting cut off).
Now somehow both these companies can make money, yet only Comcast charges for overages and yet has much lower caps.
It is just a money grab. While some kind of soft cap or throttling can be needed to make sure people play nice (we can only have Internet fast and cheap if people share, otherwise the backhaul is prohibitively expensive) low hard caps with overage fees are just used to try and make more cash.