No conspiracy. Amazon is a business, and they're doing business in a way that they believe will provide the best value -- for them. That does not necessarily equate to the best value for us, and in fact the needs of a seller (get as much money as possible for as little as possible) and the needs of a buyer (pay as little money as possible for as much as possible) are often diametrically opposed. Ideally, from a business's point of view, we'd pay everything we have and get nothing; from a consumer's point of view, we'd get everything we want and pay nothing. Somewhere in between, we come to an agreement and pay something for something, with the "something" in question subject to negotiation and market forces. Amazon is a large, successful company ... I've been doing business with them myself, by the way, since almost the day they opened ... but I don't delude myself into believing that they have my best interests at heart, any more than I have theirs.
I never said that Amazon was a fly-by-night operation (incidentally, I have one of those insulated cups they sent out on their first anniversary) nor did I say, or even imply, that Kindles had some kind of "secret speaker" or they could spy on conversations, nor anything of the kind, nor who, if anybody, they were reporting anything to (though since you brought it up, that has been done with GM's OnStar in-car microphones). I listed the things that they were known to have done already, such as deleting books (no, it wasn't just one book; it was books, multiple) from the Kindle, determining which passages you have annotated (part of the "everyone has to be like Facebook" fad of the moment), etc. I listed the things reported but not (to my knowledge) proven, such as checking for software patches despite wireless connectivity being turned off to extend battery life.
Have they demonstrated that they can brick a Kindle? No. Not yet. But it is a computer, specialized though it is, and they do have remote access to it, which they have demonstrated aspects of already. If a competent person has full remote access to a computer, they can generally disable it; hence, it is likely that Amazon has that capability. You will note, though, that was in the section where I speculated on what Amazon might do, should they choose to. Will they? Not unless it's profitable. Can they? Most probably. They have made very public missteps, like removing the sales rankings of GLBT books "by mistake"; it's not at all outside the realm of possibility that they would so something that affects the wrong people -- much like that recent government operation meant to disable 10 websites that got 84,000 "by mistake".
Simple scenario: the government tells Amazon "Kindles owned by the following 10 people are being used for child porn; disable the user's ability to delete content so we can use them for evidence." So Amazon does ... they think ... and instead of 10, they disable 84,000. Possible? Yes. Probable? I don't know. I'd hope Amazon is more competent than Homeland Security. But saying "because Amazon said they wouldn't delete your books anymore means they can't do it" doesn't make the possibility go away.
Pest control eradicates pests. DRM eradicates rights. I want my cockroaches eradicated, but I'd prefer to keep my rights. I don't buy DRM-locked ebooks.