The prime and most simple reason that RIAA/MPAA have been and are "buying" pet lawmakers is out of fear. The fear of losing a business model they thought, until the explosion of the internet, gave them total control over both artists and the marketplace.
Message One: You don't have control; you never did have control; you never will have control.
Whenever you think you have everything tied up real nice and tight, people will come up with a new way to "slip the knot". To paraphrase another notable "Star Wars" quote, "The tighter you try to grasp control, the more will slip through your fingers".
Executives in both the music and movie industries seem to think that just because they have a business model that has worked "so far", that they have a God-given right to perpetuate it forever. Nothing could possibly be further from reality. Mr. O'reilly put it very well "No one promised them tomorrow".
Message Two: The only thing you can count on as absolutely certain is that everything changes. Adapt or die!
What got you where you are today will not work tomorrow. Business survival (let alone growth) demands that you change with the times. Any company (or even and entire industry) that can't or won't change deserves to go under. The clock can't be turned back and nobody can legislate "tomorrow is yesterday".