>the human component of this system would really prefer not to be downvoted.

I agree completely with this.  This is completely rational.  After all, no one _wants_ to be downvoted.

>Part of the reason for the UI change was that people were getting downvoted and getting upset about it. Dismissing that the existence and significance of that reaction is to dismiss a huge component of this system, the human component.

The thing is that even though it is rational to not want to be downvoted, it is irrational to_get upset_ about being downvoted.  For the same reason its irrational to get upset about a bad beat in poker.  Because the very same system that allows your hands to hold up most of the time (and therefore allows you to make money) also causes your hands to get cracked sometimes.

So it was irrational for these users to get upset.  There are three ways to handle someone who is irrational:  The first, middle of the road, solution is you can do nothing.  The second way  is that you can embrace their irrationality.  The third is that you can reject their irrationality.  The advantage of embracing that irrationality is that the immediate effect of doing so will be to comfort the irrational person.  The disadvantage is that it will also reinforce his irrtionality.  The advantage to the third solution is that it might get the irrational person to think more rationally.

Consider Rudy.  Patch's roommate in the movie in the movie "patch adams".  RUdy believes that he is being stalked by an army of millitant squirrels

In this scene, Patch uses the second method to address rudy's irrationality.  https://www.youtube.com/watch?v=WfGHIl4rHw4

Note that choice 2 and choice 3 are mutually exclusive.  Patch can either try to convince rudy that the squirrels aren't real, or he can help Rudy fight the squirrels, and thereby implicity acknowledge that they are real.

If someone is irrationally upset about getting downvoted, Choice 1 would to just ignore them.  Choice 3, which is the way i would have gone, would have been to say, especially to the very well paid authors who were most vocal about downvoting, "stfu and stop whining.  the very same system that allows you to make all this money also allows you to be downvoted.  If youre taking the money, youre accepting the system"  and followed that up with an explanation about h ow  its not personal, and its necessary for the system to work.

Instead we grabbed our trusty squirrel bazooka,  changed the UI, and went with choice 3.

So changes to the UI might not have caused the irrationality, but the decision to reinforce it (versus do nothing or actively oppose it) is, perhaps, why it persisted.  (although its also possible that it would have persisted regardless of either inaction or active rejection)