Google is requiring developers explain how their apps properly use Accessibility Service to help people with disabilities in order to keep their requests for Accessibility Services. Noncompliance will mean the removal of the app from the Play Store. This is separate from the effort to make an app conform to the WCAG 2.0 Level AA guidelines. Some sites, such as Android Police, have speculated that this initiative could largely be due to security.
Read more on Google’s new requirement on 9TO5Google.