The red lines drawn by publishers - we MUST have ebook rights, you WILL accept 25% - start to look both shaky (as they are crossed by writers coming into a publishing deal from a self-publishing success) and demonstrably unfair. This is not a good game to be playing when self-publishing has never looked so plausible or so profitable. It only requires a few successful transitions to put a very large hole in the traditional publishing bucket and see writers come pouring out, and appearing to be unfair in dealings with authors guarantees a few will try to become those successes.
I hate the percentage argument, in so much as it’s frequently just a tangential pop quote bearing no relevance to the subject at hand, but the Harper Collins figures in Nick Harkaway’s Futurebook piece today do rather make the industry look like arses.