"Bull" depends upon the context.

A number of people on these forums have mentioned using ereaders because of visual impairments, simply because they can enlarge the font size and other visual features of the page. (Remember, visual impairments doesn't mean zero vision.) It is also possible to enable text-to-speech on many readers, and for many books. So yes, there is a demand.

But I would think that the ability to make accommodations is a much bigger factor. The blind can demand audio books, braille, etc., but the library can restrict their acquisitions due to availability and demand. It is a limitation of the medium after all. Ereaders are a different story though. There are no technical reasons why accommodations cannot be made for the visually impaired when there are devices with text-to-speech functionality. It would also be trivial to develop a reader that can interface with braille devices.

Or to use your art gallery example: I would have issues with them forcing random art galleries to make accommodations for the blind. On the other hand, it is a different story once they have guides (human or automated) providing tours. Once you start considering infrastructure that will allow you to make accommodations, it really ought to be a moral and legal obligation to ensure that the accommodations are made.