Well, people tend to eagerly consume what's simple. That sometimes takes education and a certain life experience to tell good things from bad ones. The same goes for any form of creativity - art, music, animation, movies, games, books - any. The portion of low-quality stuff was never really that low. Technology just made entering this area more simple. Just like printing press made books easier to make and thus opened a way for poor-written but SIMPLE books that were popular and profitable. But this also opened a way for some really talented people who otherwise wouldn't have a chance for their creations to see the light of day. As time goes and people get more educated and experienced, the balance between "easy to digest" and "better but complicated" content shifts towards the later, so I hope the same will happen with the internet content.
P.S. Yes, plastic porn sucks (in a bad way). It's so hard to find truly passionate and beautiful NSFW content now.