100% agree about the UX problems. Most engineers would be happy to fix those issues, but of course, companies always want the new features...because that's what customers want and what drives more $$$.

Sadly, it's true that the % of new sales generated by improving a11y beyond the bare minimum isn't going to be terribly large. That's why it's important to have regulations that mandate decent support, because the monetary incentive that drives corporate behavior just isn't there.