Quite a few potential reasons including network strain, the inability to prioritize business customers, potential legal fees every time netflix is laggy, the other aspects of something being a utility such as their legal responsibilities when having to deal with customers being more obtuse.
But more so I think there is one key thing and you reference it in your list
They would however would it placate the average consumer if it seemed that ISPs were indifferent to the law, essentially if it doesn't make the companies whom everyone hates suffer then why would it gain support, its quite a good strategy if it is planned but given that Obama was quite chummy with Comcast executives I doubt it really affects them in an extreme manner regardless.