Whilst I take the point that everyone's at it anyway (data capture that is!), I'm not sure I follow the argument that a bit more of it doesn't matter. I've only been on MR a month and hadn't seen previous threads on the topic, but having looked a bit further it's interesting that some MR Kindle owners were concerned enough about it to try to write a hack to stop it happening, see
this thread.
I guess it does come down to a trade off - if what Amazon offers in terms of service makes it worth agreeing to them doing all this other stuff (and what this other stuff amounts to seems to be less than certain), then that's fine. For me, when I was looking at the Amazon site with a view to buying a Kindle as a second reader this morning I was brought up short by what I was required to agree to. So, for now, I'll continue to side load stuff on to my unconnected, unsynced European IREX DR800 - and feel, naively, a bit safer for that.