I'm not sure what your definition of mainstream is, but I commonly see text-to-speech listed as an advertised feature of mainstream consumer products.
TTS's dirty little is that it's actually much faster to read something yourself than have something read to you, assuming you are fluent in the language. It's not a failing of TTS, it's just people not properly considering the use of technology. The same goes for the roomba and the programmable microwave. It makes much more sense to have small single-purpose robots that function well, than a single multipurpose humanoid robot.
TTS's dirty little is that it's actually much faster to read something yourself than have something read to you, assuming you are fluent in the language. It's not a failing of TTS, it's just people not properly considering the use of technology. The same goes for the roomba and the programmable microwave. It makes much more sense to have small single-purpose robots that function well, than a single multipurpose humanoid robot.