I apologize to all who are in favor of this type of proposed loophole to proper web development, but I am going to have to say that I have only seen one example of a case where this API could be useful and in my opinion there is no need to provide a generalized loophole that introduces all of these other problems when there is already an easy fix that is already implemented by the company that was targeted by the example.

Google docs and any other web apps that run into that performance degradation problem could take the Gmail approach and provide a link to the accessibility rich text only version right at the tip top of the page. We’re dealing with simple cases of minorities and majorities here. The web is finally getting to a point where when you design properly it works properly. There is no need to encourage people to start taking the easy way out when so much work has already been put in to make creating accessible content a pretty trivial task for the majority of web sites.
Someone mentioned the good old “alt” tag in a different comment, and this brings up a point that I think should be stressed on each and every discussion regarding accessibility. While this tag is nice, one, it is rarely used to it’s full potential, and two… Accessible web content all too often seems to be defined as just using this tag. I can’t speak for all, but I can surely speak for this low vision user. Using aria-label or a label for element on your form fields is WAY more useful to me than alt=”A picture of a cat”.
Another huge useability problem that is often overlooked is the presence of in-text links. If you are going to work on an API to make things better for everybody involved, please make that one. Doing so would allow pages to be easily read by screen readers without needing to rewrite 99% of the internet. Lets focus on users not Google’s bottom line. I’d much rather click a link than have to okay anything anyway. If you’re already going to build things twice, just link to it in this way and BAM… Problem solved. You know, now that I think about it more, the needed API was one of the first elements on the web. It’s the A HREF if you need an acronym. Now lets feed starving children.