People with disabilities can use specialized devices, which are made available only by prescription to people with a qualifying disability, that play copies of works produced under an exception to the U.S. copyright statute (17 USC 121). Kindle 2, being available to all, does not meet this requirement.
Have you ever used devices dedicated to the blind. They are expensive, ugly, complicated to use and do not offer what the Kindle does.
Being legally blind with functional vision, I like to read, but I cannot for long periods of time. With the Kindle 1's largest font, that eye strain is reduced somewhat. The Kindle 2 is the next step towards my ideal reading device, one that allows me to go back and forth with large print and TTS.
Losing TTS (Amazon's discussion is likely tantamount to this) will kill this move forward for accessible, aesthetic and feature rich device for the partially sighted.
See One Small Step Back for Amazon, One Giant Leap Backwards for Access for more of my rantings on this subject.