Naively it might seem as though, with access to so much more to read (blogs, electronic journal access), we should all be reading more. But mostly we're not. I don't think this is accidental, and in fact it's partly caused by the increased access. I hope to write something longer and more careful on this, but here are a few brief thoughts for now. They're all roughly economic in orientation.
(1) More opportunities drives down the value of individual reading episodes, so procrastination costs less. When I was a nipper some things I had to read were only available in paper copies and in small numbers. For example, in my first year at university several of my courses had compulsory readings that were in the "reserve room" at the library. With, say, 150 or so Political Science 1 students and four copies, you mostly had to book a session with one of the copies - if you didn't make good use of it, you had to go through the whole process again, so you read carefully and made good notes. Now everybody wanders around with loads of PDFs of stuff that they "should" read, but can start reading almost any time.
(2) Having more available at any time (which the web and big private collections of electronic papers and stuff) drives up the effective opportunity cost of reading any one thing. This makes it easier to justify "foraging" around superficially, trying to work out what to read properly.
(3) The web has made the costs of distractions close to zero. Again, when I was a nipper working by myself at night, if I wanted to mess around there was less TV to chose from, and social interaction usually meant making a phone call, or maybe wandering around the university residence to see who else was awake. Now I typically have two email accounts and facebook running in tabs on my browser at the same time as I've got a PDF of a paper open in another application, or a draft of something I'm reading open. With the transaction costs of starting to waste time so low, it's also not surprising many of us take so many more opportunities to interrupt ourselves.
What can we do? Well, we can partly manufacture scarcity, by working off-line. I now do some of my best reading over lunch or coffee, when I go to a restaurant without my laptop, and take only one or two papers with me. I also get more and more reading done in meetings, since I've found that you really can read one thing and follow the discussion around you pretty well, as long as the layout of the meeting doesn't make it too obvious to others that you're doing two things at once (some folks feel neglected or seem otherwise mildly offended). We can also learn, and most of us seem to, that the apparent low cost of procrastination is partly an illusion - our time is still scarce, even if the start-up costs of an individual reading episode are lower.
Those of us in the teaching business not blessed with hyper-competitive students, also have some head-scratching to do working out how to help those we teach do more proper reading.
(Acknowledgment - Tim van Gelder wrote something I read a while ago about how photocopying had hurt reading. I couldn't find a web version to link to, or even find a version I might have downloaded on my own PC, but when I can I'll give proper acknowledgment here.)