I'm always astounded by the hard-sell and oversell antics of some indie authors. While I often advise indie authors that they must be able to take off their Author hat and put on a Publisher hat, the thing is, no matter which of those two hats they're wearing they should always have a Reader beanie on underneath.
While I wouldn't ever advise a writer to engineer his or her fiction to suit a given demographic, this is definitely required when it comes to nonfiction. You must do this in order to identify your target audience and ensure your book contains the information or reference material that audience will want. But having said that, I'll go on to say that even fiction authors---even literary fiction authors---would do well to give a thought to the reader as they lovingly craft their prose. You want to see your vision brought to vivid life on the page, certainly, but you don't want to confuse or bore your readers in the process.
It's even more critical to keep your Reader beanie on nice and snug when you go to don your Publisher hat. This is necessary because among other things, you still must identify your target audience, regardless of whether your book is fiction or nonfiction, in order to develop an efficient and effective marketing plan. You need to figure out who's most likely to be interested in your book, and where and how to reach those people. But this doesn't mean that once you've done so, you should go all full-bore, Mad Men, Marketing Exec From Hell on them.
Author and Publisher you may be, but you're also still a human being and a consumer. You still shake your head in annoyance at the pile of junk mail, junk email, junk fax and even junk Facebook and Twitter flowing into your life on a daily basis, don't you? So why on Earth would you ever risk being counted among the purveyors of that junk?
How is it possible that the Author who chuckles to herself at over-the-top marketing hype in advertisements for weight loss aids will nevertheless splatter "MY BOOK WILL CHANGE YOUR LIFE!!" in gigantic, flashing red letters two inches tall on her author website?
How can the Author who complains about all the pointless piano-playing cat videos his Facebook friends post to his wall go on to blast all his Twitter followers with twice-daily reminders of his book's current availability and sales rank on Amazon?
Why does the Author who's sick of all the spam comments left on her blog turn around and post a so-called review of someone else's book in which she devotes as much time to plugging her own book as talking about the book she's supposedly reviewing?
Yes, you must get the word out about your book. But you most do so with some consideration for the people on the receiving end. When in doubt about a given tactic you're about to employ, put yourself in the shoes of a non-writing, non-publishing, ordinary consumer and imagine how your tactic will be received under those circumstances. Don't overthink it, just go back to the Golden Rule: advertise how you'd want to be advertised to.