In the Guardian, self-publishing academic Dr. Alison Baverstock addressed some misapprehensions about DIY publishing. Partly this meant addressing general prejudices (all self-published books are rubbish, etc). Partly it involved a reality-check for those who publish or intend to publish.

Among the key points:

Self-publishers often don't think before hitting send:

Material made available without sufficient thought damages not only the writer’s reputation but that of self-published work in general. Typing is not the same thing as writing.

They often don't think about layout and presentation

Publishing is a different skill from writing, and laying out content to ensure it is easy to read takes research and practice. Effective publishing is not just pressing a button.

The commercial success of self-publishers (aside from the poster boys and girls) is often hard to track

Self-publishing authors tend not to get in included in surveys of authors’ earnings, but Orna Ross, founder of the Alliance of Independent Authors, says: “Many of the association’s members are earning significant salaries now. I’m not talking here about the outliers, like the Kindle millionaires, but the many who are earning enough to leave their day jobs, feed their families, pay their mortgage, afford comforts and luxuries. And let us not forget that sales doesn’t just equal money, it equals readers. It’s one of my great delights to witness what this does for their confidence in themselves and in their work.”

Traditional and independent publishing can be complementary:

At its best [self-publishing] offers the traditional industry a new source of writing talent and a chance to take on material with readerships already established. In the process, it cultivates the kind of author proactivity that publishers need if they are to reach markets that are no longer predictable, due both to the proliferation of new media and the challenge to reading of so many other alternative leisure activities.

Value in self-publishing is much wider than sales or even readership:

Interviews with many self-published authors have taught me that there are often issues of more importance than sales. For many, the material they want to publish has long burned inside them and the process of self-publishing delivers a profound satisfaction.

See also Maggie Brown's Observer piece on the female stars of self-publishing.