IP does not exist. It's a figment of our collective imagination.
Exactly this. When copyright was at a sane length, the reason for it was so you didn't release a work and have that work immediately re-released by a dozen shady publishers who didn't give you a dime for your efforts. When something like that happened, it was a serious threat to creativity. After all, why work for years writing a great novel just to have six publishing companies steal it, print their own editions of it, and not give you any money for it. Worse, their editions would compete with your own edition and you would be making less sales/money as people bought the "wrong" edition.
The balance to this, though, was that your temporary monopoly only lasted a short time. After 14 years (28 years if you filed for a one-time extension), your work went into the public domain and almost all bets were off. You still couldn't republish it and attribute it to someone else, but you could write a sequel or base another work on it without the original author's consent.
This went fine for the most part until copyright holders saw the works entering the public domain and envisioned dollar signs leaving their pockets so they got the copyright terms extended again and again until they are, for all intents, perpetual. If a work is created today, is corporate-owned (so we don't get into "life of the author", and the terms aren't extended again (the latter being a big IF), my 8 year old has only the slimmest of chances of seeing that work in the public domain. (He would need to live to 103.) If he has a child at 25, my grandchild would see the work in the public domain when he turns 78.
I know we love extolling thinking long term, but what possible incentive does it give knowing that a work you create in 2015 will only enter the public domain in 2110?!!!