Of course this was bound to happen. I have already seen three people who have decided the lack of a Pulitzer Prize is because of the surge of indie authors and the poor quality of some of the work. These people don't seem to realize such a link would only work if we thought the jury read those indie books and judged them with the others or if traditionally published authors were being influenced by indie authors, and their publishers were going along and allowing poorer quality material to be published.
The unfortunate truth is that the traditional publishers simply didn't publish a work the others could agree was worth the prize. It's happened before: 1941, 1946, 1954, 1957, 1971, 1977 and now 2012. None of us can say why they didn't find any of the books worthy. I'd been hoping for Swamplandia! They decided none were worthy of the honor.
If there is a decline in the quality (and not simply a year when the proper book didn't appear), then perhaps people might look towards the school system and the deplorable and declining state of education over the last 40 or so years. While imagination is an aspect of individualism, training makes the writer. People who come out of the school system without a clue how to write a sentence, let alone a book, start at a massive disadvantage -- and yes, many of them leap into self-publishing, which is unfortunate. Most don't even realize they lack the proper education because they've been told they learned everything they need to know. After all, they passed their grades and they graduated. Many went on to college. They still can't write a proper sentence.
They can learn, but this might take them longer, and only if they finally come to realize they lack crucial knowledge. Perhaps we're dealing with a backlash in the educational system because, honestly, there is no reason why indie authors can't write well if they knew how. The technical side can be fixed. Imagination may not always be up to story-telling, but that has to be judged in an entirely different light.
I can't help think blaming a lack of good material in traditional publishing on indie authors is like saying apples aren't as sweet because oranges exist. They're both fruit and they both grow on trees. There is no way the existence of oranges creates bad apples.
While it is common to blame some other area for a (perceived) fault, at least try to be logical at where you put the blame, if there is any blame to be given. Maybe all we are dealing with is a change in style that the jury didn't like. Perhaps the style of literary fiction is reshaping itself, and old standards will eventually pass away. After all, The Magnificent Ambersons is not written in the same style as The Grapes of Wrath and neither read like Beloved.