P2P isn't a form of marketing. The vast majority of music that is being "shared" by the vast majority of P2P users is music that people only learned about because of the millions of dollars spent by the record labels in actually marketing it.
Sure, some of it's payola, but there are lot of other legitimate marketing activities (videos, advertising, press, retail distribution and support) that don't have that taint.
Intellectual property laws were authorized by our Constitution for the purpose of making the public domain richer in the long term at the cost of allowing government to make laws making authors richer in the short term. Nowhere does it say anything about protecting record labels, publishers, etc.
You're right, but the Constitution also gave the Congress the authority to pass laws that provided penalties for infringing those authors' rights in the short term too.
Right but I'm having a little trouble finding the clause that enables our government to regulate the ability of devices to play media.