Patri Friedman precisely expresses my own views on intellectual property. I am not confident enough to come out entirely against IP, but I am doubtful of the benefits of having it at all.
The strongest - but not the only - argument against it, as I've said previously, is the cost of enforcing it. Friedman quotes Paul Phillip saying "Enforcing IP law in the 21st century will require government intrusion on a level we can barely imagine".
I can see no argument against drastically reducing the term of copyright (here in the UK a bill is being proposed to increase the term), and no argument in favour of increasing the scope of IP law into areas such as film plots and fashion styles.
Like Patri Friedman, I have to accept that "you aren’t going to see a few people whip together Lord Of The Rings for fun anytime this century". However, the feature film is one possibility among a huge range of possible styles of entertainment, and many of them, unlike feature films, can be produced incrementally. It doesn't immediately occur to you that, faced with producing something on the scale of LOTR without copyright to give you return on your investment, you have the whole world of previously-produced films to use as raw materials. It is difficult to produce a feature film incrementally because you need to use the same actors all the way through, but animated films, for instance, do not present that same difficulty. It is clear we would lose some things without copyright, but it is not at all obvious what we might gain in return. In the cases of the proposed regimes for fashion or stories, however, we can say with confidence that nothing those industries have produced in the past could possibly have been created had the proposed regimes been in force at the time. Every film without significant exception has been derived from earlier stories, and every piece of clothing is derived from earlier garments.
Therefore, I suspect (but cannot prove) that the space of entertainment products that could be made without copyright but not with it, is much larger and more valuable than the space we are familiar with, of products that can be made with copyright but probably not without it.