The Amazon-only e-book problem

I have a Nook e-reader, and when it goes kaput, I'll switch to some kind of Android or Windows tablet-- maybe even Kobo, who knows.  


I won't buy a Kindle, because I've worked in bookstores and know how Amazon's price gouging (it's not "competitive pricing," it's a monopolistic clubbing to death of competitors, until there's nobody left) has affected both indies and other big-box retailers.  I won't buy an iPad, because I don't think Apple products are as state as the art as they think they are and if I'm primarily using the device for reading and maybe the occasional email or web-browse, why the heck do I need a camera?


What I don't understand is why so many e-publishers and authors are going Amazon-only.  Is it a condition of e-publishing with Amazon?  Do e-publishers not know about Barnes & Nobles' pub-it extension to let you self-publish to .epub format?  Do e-publishers not know about Calibre and its brethren?  Do e-publishers simply not care about readers who aren't mass, lowest-price-only consumers, or readers of e-formats who would prefer to use something that isn't just the path of least resistance?  


I generalize, wildly, even, but I am curious, too.  I haven't read the terms of any of the Amazon self-publishing contracts.  I know that some of the third-party "self-publishers" like CreateSpace, et. als., used to require you to use their format for a certain blackout period, but I wonder if authors think it's worth it versus the share of readers who don't own Kindles and/or use the Kindle app on their overpriced iProduct but who might, otherwise, buy their book.


I've been attracted more than once in the last couple of months to information about books that I'd love to download-- only to find out they're Kindle-only.  And inquiries to the author go unanswered.  It's too bad, because a DRM-free, multiplatform publication would seem to be the answer to reaching the maximum audience... I find it hard to believe that authors-- who write all day on a computer-- can't figure out how to use more than one electronic publishing format.  


Anyone have any experience with the pros and cons of why authors would turn away potential buyers, just because they don't own Kindles?