Have you ever worked in a corporation? Do you really think that Windows 8 UI was the fruit of years of careful design? What about Workday?
> but it is bizarre that so many businesses seem to be discarding battle tested UXes for chatbots
Not really. If the chatbot is smart enough then chatbot is the more natural interface. I've seen people who prefer to say "hey siri set alarm clock for 10 AM" rather than use the UI. Which makes sense, because language is the way people literally have evolved specialized organs for. If anything, language is the "battle tested UX", and the other stuff is temporary fad.
Of course the problem is that most chatbots aren't smart. But this is a purely technical problem that can be solved within foreseeable future.