It's not that bad, since the Kindle 2 doesn't have any compatibility limitations compared to the Kindle 3.
It's not like Amazon has moved to a format that is Kindle 3-only. The K2 can access all the same media, and ebooks released in 2011 won't strain the K2 CPU any more than ebooks released in 2009. It just has a somewhat lower-contrast screen and a little less storage (which is not a big problem given the small size of ebooks.)
ie, it's not like buying an original XBox after the release of the 360.
