Up-front disclaimer: I work for a university press and have worked there for fifteen years as of the end of this month. I do not speak for my employer, the university, the state, the university press community, etc. etc.etc. That being out of the way….
Self-publishing is a perfectly legitimate endeavor. If you want 100% creative and marketing control over your work, or if you want to receive 100% of the profits from your book, self-publishing is the only way you’ll get that. If you regularly do lectures and have a built-in venue to sell your books, or if you’re an expert in a narrow area and you know how to reach the other people interested in that subject, self-publishing can work very well for you. Doing your family genealogy? Writing a book that’s of great interest to people in your small town but limited interest to anyone else? Great! Publish it yourself!
I’d even argue that some of the vanity publishing services can be worth the money for some people. I can readily imagine, say, a well-off lecturer who wants a book to sell on their tours but who’s too busy to do all the legwork of getting an ISBN, finding and hiring a copyeditor, designing a cover, etc.; for them, it may be worthwhile to pay a flat fee to a service to get these things done for them.
But the more I’m reading about Harlequin Horizons, the more little things bug me.