Hm. Granted that Amazon is a corporation and is interested in maximizing profits, let's consider a couple of other points of view here.
Amazon comes out with a new ebook system. Why not use an existing reader, e.g. Bookeen? Why on earth would they want to get into the hardware design business, not their traditional line and possibly a big risk?
One obvious reason is because none of the other ebook readers offered the kind of ease of use Amazon wanted to offer, because none of them had a cellular network built-in. Amazon wanted to make a reader you could browse the store and purchase books from. That would take more input options than any of the other devices had, in addition to better connectivity.
Having gone into the device design and provision business, I'm sure Amazon wants to recover their investment. But I think there's another reason they've locked Kindle books so tightly to the Kindle. I think it comes back to the publishers, wanting "tough" DRM to prevent those awful evil pirates from stealing their IP. I think the publishers who were never willing to go with ebooks before were talked into it by Amazon in part due to promises made about how hard it would be to crack the DRM on these books. I think everyone involved was looking at the iTunes model and trying to figure out how to emulate it as closely as possible... just as Apple itself was moving away from DRM.
Personally, I think this was misguided at best. Amazon's use of a variant of Mobipocket was, in my mind, what finally drove the cracking of the Mobi format.
It would not surprise me at all if someone eventually either provides a common, simple workaround to purchasing Kindle books without a Kindle, or goes to court to force Amazon to open their Kindle book sales to non-kindle owners.