Rand-Hendriksen believes that the accessibility-ready tag should be required for all WordPress themes.

Um, no.

Yes, there's an "accessibility-ready" tag. But behind it are a set of draft guidelines that only one or two people know how to use to review Themes, and that are still being worked out, because there are no established, best-practice ways to implement them.

We've gotten a ton of pushback on implementation of the existing Theme Review guidelines, from the initial Guidelines to the revisions/improvements made over the past four years. But we have operated under a very effective approach: first establish best practices, then focus on education (teach developers how to implement those best practices), then make the best practice Recommended, and then, once the practice is in common enough use that we think it feasible for everyone to follow/implement, make it Required.

Rand implies that implementing the accessibility-ready Guidelines is all but a trivial matter for Theme developers. I beg to differ. And the crushing workload of forcing what is currently a one-man accessibility review team to review every single Theme submitted to WPORG would grind the Theme Review and Approval process to a halt.

Do we need to get there? Yes. And eventually there should be a set of accessibility-related Guidelines that are Required - either a revision to or a subset of the current draft Guidelines. But it's going to take time.

Given the reaction from Theme developers that I got to the suggestion that we make implementation of Theme Options into the Theme Customizer Recommended (not even Required; just Recommended), I can only imagine how Rand's suggestion would go over.