I have been growing increasingly insistent that scientific publishing should move toward open access. This is caused in part because, as an employee of Google, I have very little access to commercially published literature, in spite of the fact that we drive most of their traffic. For example I have access to almost none of the economics literature.
One great advantage of open access publishing is the lack of backlog – journal articles could become available on the web the moment they are accepted, there would be no practical limit on the number of papers accepted. When the flow of high quality articles gets too high, you publish more papers. When the flow of sufficient quality papers dries up, you publish fewer papers. There would also be no practical limit on the size of articles. Moreover, it would make it easy to maintain links to backing evidence for scientific literature, including demos, data, code to process the data, designs of experimental apparatus, etc. This would enhance overall quality, by removing the artificial constraints of page limits and focusing exclusively on quality.
There are numerous advantages, and as far as I can tell, few disadvantages. The only significant barrier is lack of vision.