If the ISP wants to be involved in monitoring and regulating (or charging differently depending) where your packets go, then they can be liable for providing child pornography, being a party to all copyright infringements, etc... If they want to take action depending on the data, then they can be held liable for the data as well. This is why the telcos wanted "common carrier" status in the first place.
But now they're too greedy having seen the cable TV model where they get to charge rent on both ends for content they didn't even create.
Regarding ISPs creating original content, they have tried that and the quality of their stuff just couldn’t stand next to Google, Facebook, etc.
I think we all know a relative who used the “install CD” that came with their 2000s-era ISP and ended up with a junk homepage & browser toolbars, and “ask Jeeves” as their default search engine.
But now they're too greedy having seen the cable TV model where they get to charge rent on both ends for content they didn't even create.