I had noticed that most of the Icons we see of biblical seens are related to the Sunday Gospel reading, I think it may be as the sermon on the mount is rarely if ever read on Sundays it has not been a subject of interest for most people until more recently as if I remember rightly the passages from the sermon on the mount are most commonly read on weekdays so less heard and less depicted.
I suspect that the frequency of depicting a sean is related to how often the passage is heard in Parishes (so on a Saturday, Sunday or Great feasts). I also have a suspican the technicality less complicated icons are preferred by the iconogriphers, given what a friend of mine who is an iconogripher said about the process of preparing to write an icons. The scarcity of these icons is probably a mixture of few people making them and few commissioning them.
this is my take of the situation, I may have got the wrong idea but this is how I see it.