Maybe Asimov didn't think that the described scenario would be the state of the art for UX at the time, but that there would be other reasons for that UX. Maybe without some sophisticated ritual and human involvement the process wouldn't be accepted by the people? Many of our institutional, and democratic, processes involve extra steps and rituals, sometimes anachronistic, and maybe this is meant to be a reflection of that?
Perhaps the creators and operators of the machine also want it to have to complicated UX out of self interest. This could be a way of staying involved and/or retaining some control over the machine and its use.
I'm just speculating without any knowledge of the story in general...
Look at Japan, they still use Fax for everything. Sometimes once a UX or system is accepted it hard to replace it with another system, even if the newer system appears to be better.
Perhaps the creators and operators of the machine also want it to have to complicated UX out of self interest. This could be a way of staying involved and/or retaining some control over the machine and its use.
I'm just speculating without any knowledge of the story in general...