I don't find it incredibly difficult to imagine that they took the opportunity to "improve" the format for possibly performance-related or toolchain reasons. Amazon are not really focused on ensuring backwards-compatibility, they probably can't even imagine why someone would use a non-Kindle.
It's enough
for them that other Kindles can read the format.
Thing is, anyone who wants to escape the Kindle hardware ecosystem has ample options for doing so, since Amazon
still hasn't obsoleted all the many old ways to do so.
And anyone who is interested in doing so already knows that.
So once again, Amazon
may be doing things to
lock down streamline the user experience, but they aren't trying very hard -- they are only performing a token gesture.
Token gesture -- typical Amazon move, just about says it all.
