I think that providing an audio option to learners is an excellent way to personalize & accommodate learners' preferences as well as to ensure m-learning meets accessibility standards.
M-learning design that does not anticipate and meet the needs of learners with all sorts of challenges and preferences to my way of thinking only does half the job. For example, heavy reliance on visuals & images (icons, logos, etc.) to guide the learning experience is great shorthand for sighted learners, but is not nearly so helpful for people who don't see well and who could benefit from an audio caption equivalent. Also many text-to-speech readers don't read slides or jpgs. On the other hand, an adult learner who is familiar with content or doing a review may find it faster and more effective to hear (esp. if the speed can be bumped up) rather than re-read all the text content. Finally, although high level designers with access to experienced media and graphics/animations teams may have moved beyond slides & narration, many of your everyday teachers and instructors who will want to use Adapt to get their content into a responsive online format will have not. They need a tool that will enhance and complement what they already do and to help them move towards effective blended learning. Audio should be a big part of that.
I think rather than dropping audio, it would be more helpful to make it easier to integrate it into the overall design of a course. (BTW: the same goes for text captioning of visual elements and videos.) The more options for getting learner involved with content, the better. I don't feel this flies in the face of the 'redundacy' caveat in e-learning but instead provides learners with ways to make a course fit their needs and wants.
P.S. I did a fully online Master's degree, was a high school & adult ed. teacher for 35 years, have developed and moderated e-professional development mini-MOOCs for other educators, and am now struggling to design a collection of open source basic skill development apps. I'm eagerly awaiting the release of the Authoring Tool.
Does/will it have an html block so one can develop content using another tool (such as Hot Potatoes or GeoGebra), grab the code, and integrate it directly into an Adapt Learning framework?