"Unlike say, horses and buggies, it's not clear that there's a superior alternative here."
"Better" is subjective. I think a system is "better" when it ensures that people can access entertainment regardless of their income, all things being equal.
Could we monetize entertainment without sacrificing such things? Surely we can. We can have serials, for example, such that the next installment will not be released to anyone until enough money is raised. We can make movie theaters an experience worth paying for, rather than focusing on the movie itself.
This same sort of argument -- "we have no alternatives!" -- was made when automobiles rendered animal-based transportation obsolete. Pedestrians might be struck by cars! The speeds are too dangerous! They are so much noisier than horses! Yet in the end, the car was "better" than the horse, and now we face riots when gasoline becomes scarce.
I think the same is true of the Internet, when it comes to copyrights, photography, post offices, and so forth. When I was a child, photography meant film, and you had to drop film off somewhere to have your pictures developed. Then digital cameras came out, and for all the complaints about quality (remember when 1 megapixel was a big deal?), the film camera business fell apart. It was not just that we had digital cameras, it was that digital photographs could be transmitted to anyone with an Internet connection at no real cost -- whether you sent one photo, or a hundred photos.
Is it clear that digital is "better" than film? It all depends on your definition of "better." Film has more pixels at lower cost. Digital still won, and it wins even when the pictures are taken using cell phone cameras. Digital present society with a new set of problems to deal with, like the ease with which pornography can be made (middle school girls can be tricked into taking pornographic photos of themselves and sending those photos to men on the Internet, etc.), but nobody claimed it was a panacea; it just solves the problems people actually care about better than its predecessors.
The same argument applies to entertainment. People do not really care about quality; the continued popularity of camrips, and the continued popularity of low-end, unoriginal movie franchises should be proof enough. People want entertainment quickly, they want no restrictions on when and where they can watch it, and they want to be able to go into work the day after a show aired and laugh about it with their coworkers. My mother does not care about copyrights or DRM laws when she rips DVDs and copies the rip to her tablet -- she just wants her favorite shows on her most portable computer when Internet service is not available.
Copyright is obsolete because it encourages a system that makes all of the above expensive or difficult, and because there is another system that makes all of the above less expensive and less difficult. Cars get people from point A to point B faster and with less expense than horses; nobody cared about the noise, pollution, or danger. The same is true of copyrights: nobody really worries about the risks copyright lobbyists whine about when they download a torrent, because copyrights don't deliver what people really want nearly as well as the Internet does.