In order to produce material, a certain amount of resources are necessary. The mechanism we've adopted for allocating those resources is the market. For much of present production, the fixed costs of production are high -- writing a book (particularly a textbook) is a large initial investment. Same goes for software. The marginal costs of production are low -- hell, you can download a 400 page text off of Project Gutenberg or stream a movie in a few seconds with a decent broadband connection. Amortize the costs of your laptop (a few hundred dollars for a basic model, a grand or two for high end), less for tablets or eBook readers), and a broadband subscription, and it's still cheap.
Textbooks generally do have to be updated every so often, though annual revisions are pretty ridiculous, and much of the industry is a fat scam, especially where the professor teaches from his own text. Rental schemes, "authorization codes" (required to access other materials), and the like factor into this as well -- they're akin to various tack-on fees for air travel. And there's a whole burgeoning movement for producing DIY book scanners and the like (pretty fascinating, do a quick DDG search or hit up Fixyt.com for videos). One thing I've come to realize about many commercial opportunities is that they require a control and toll-taking point. Revision updates, exercise questions, registrations, rentals, and the like, all create an arbitrary tollgate. Great for the publisher, for the student, not so much.
And the model requires that for a new or continued revenue stream, new books have to be published. I'm beginning to strongly suspect this is a market failure -- of externalities (the educational value of those books benefits more than just the reader) and perverse incentives.
The question is: what's the better way? Online we've been experimenting with vastly democratized publishing, and the result is Upworthy, Buzzfeed, HuffPo, and numerous other viral sites, which with time are finding their way into my hosts file with '0.0.0.0' entries, and search-engine blocklists. It leads to what Clay Shirky recognizes as a problem, not of data overload, but of filter failure.
There's also the problem within the publishing world, including academic publishing, of so much material being produced that not only is it not possible to keep up with it, even within a discipline or sub-specialty, but that good content is getting buried. That's the real tragedy of broken filters -- not the crap spewing everywhere, but the gold nuggets that don't float up.