The idea that Amazon would disable text to speech at some time after purchase is disturbing.
Is this the entire story? What were realistic assumptions at the time of purchase? If one purchased a book or even the Kindle assuming in good faith the one could LISTEN to a Kindle book, changing the rules is just wrong. Audiobooks are a unique market and I understand purchasing a product specifically for this purpose. Amazon obviously has a much larger selection than Audiobook (which is the service I use). Text to speech seems a reasonable alternative to professional narration for reasons of cost or availability.
This issue with the Kindle has been confusing. I had once thought that the speech function had been disabled and I was surprised to learn that the option was still available. This ambiguity is problematic. Perhaps a clear disclaimer would do the trick, but retroactive actions seem a really bad decisions by Amazon.
Kindle Issue