Yes, it's true that Amazon allows you to publish and market your own stuff to the Kindle, and at a very attractive-seeming royalty...but that model allows you to publish ONLY to the Kindle.
You don't see Amazon "fighting" to keep prices down on .pdf or epub files, just Kindle-friendly ones.
If they do what they seem bent on doing, and drive other e-book readers, as well as paper books, off the market, then you, the reader, are only going to be able to get your reading fix on Amazon.
What's worse from my perspective: if Amazon has their way, writers are only going to be able to publish with them. And if that happens, how long you think that sweet royalty will last?
Amazon isn't trying to expand e-publishing. They're trying to contract it to one machine, the one Amazon makes.
It's a bad idea. Fight it.