From Cognitive Surplus:
"Scarcity is easier to deal with than abundance, because when something becomes rare, we simply think it more valuable than it was before, a conceptually easy change. Abundance is different: its advent means we can start treating previously valuable things as if they were cheap enough to waste, which is to say cheap enough to experiment with. Because abundance can remove the trade-offs we're used to, it can be disorienting to the people who've grown up with scarcity. When a resource is scarce, the people who manage it often regard it as valuable in itself, without stopping to consider how much of its value is tied to its scarcity. For years after the price of long-distance phone calls collapsed in the United States, my older relatives would still announce that a call was "long distance." Such calls had previously been special, because they were expensive; it took people years to understand that cheap long-distance calls removed the rationale for regarding them as inherently valuable.
"Similarly, when publication--the act of making something public--goes from being hard to being virtually effortless, people used to the old system often regard publishing by amateurs as frivolous, as if publishing was an inherently seriously activity. It never was, though. Publishing had to be taken seriously when its cost and effort made people take it seriously--if you made too many mistakes, you were out of business. But if these factors collapse, then the risk collapses too. An activity that once seemed inherently valuable turned out to be only accidentally valuable, as a change in the economics revealed."
(Shirky elsewhere discusses how, yes, being able to publish at the push of a button means we'll see a lot of crap published--but we'll also see more experimentation and variety in what is published, as publication is no longer tied to the need to make a profit and appeal to a large swath of consumers; a book doesn't need to be a "guaranteed bestseller." Before movable type, the average book was a classic--only canonized "great books" saw paper, because they weren't a risk. Movable type paved the way for cheesy romances, throwaway lit, etc--but also for more risky writing. Same with the "publish" button on blogs or elsewhere on the web. Poetry has long been in this kind of model, I think--to some extent it seems, now, as if all the world's not a stage--but a small press.)