I also agree that the concept of copyright is a 'legal fiction' in the sense that it's a kind of hack. 'People who make intangible things should be able to get paid, so let's pretend they are physical artifacts.' But the purpose of that hack is at least in its purest sense noble. Child labor laws are also a legal fiction. There is no natural reason for them to exist. We made them up because we got tired watching the children of the poor be used up as a consumable good. Nature sucks. Civilization is a conspiracy to escape the brutal amoral Darwinism of nature.
If you want to get rid of copyright, create a better alternative. But your better alternative must do the good things that the original does, otherwise it won't work. So far I don't see such a thing.
The fundamental issue is present here in this sentence:
"Nowadays, film and music are just files, and can be freely copied at will."
Let's say I have two files. One is a music file, the other is the output of /dev/urandom. They could be of equal size, and they are equally easy to copy. But one contains the results of possibly thousands of hours of human labor not to mention the irreplaceable and ethereal quality we call 'creativity', while the other contains no actual information at all.
Conflating one with the other based on how easy they are to duplicate amounts to a profound devaluation of human labor and human life.
The same sort of argument sounds absurd when applied to physical goods e.g. "a t-shirt is just cotton, so why do we have to pay a premium to a bunch of factory workers?" But it is in fact the same argument, since in reality everything is just information and therefore all labor amounts to the transformation of information. Your t-shirt is just carbon, hydrogen, oxygen, etc. organized in a particular way.
(This argument carried further gets really interesting, but I have work to do. Quick version: in a post-3d-printing future where everything is automated, copyright might well be the only form of property and the only mechanism for compensation available to the non-capitalist class.)