Until very recently, genealogy has been very unfamiliar as a hobby in NI. People in country areas were often or indeed almost always very aware of who their kin were, probably in a rather undefined way, but anyone who actively sought information about past generations would have been regarded as unusual. It is well known that
Irish records are very scanty, but I think also there was a more psychological reason why
Ulster people didn't think too much about their family history. So many family members in succeeding generations left for different destinations that those who remained in Ireland lost touch with such large numbers of their kin that I think a kind of protective amnesia developed. They knew they would never ever see them again, so they almost deliberately stopped thinking about them, as a way of protecting themselves from the trauma of loss of loved ones. It seems to me that this is still somewhat in evidence, when you get a negative response from an individual in NI, though I do think it is changing. Genealogy as a hobby is becoming more evident in NI life, and increasingly an understanding of the genealogical way of looking at history is becoming more widespread.
I stress that this is my own theory to explain the phenomenon which you mention; I have never seen it discussed or documented, but I think it explains a lot about some aspects of what historians call the "mentalité" of
Ulster. It may even partly explain the doubts about identity and security which are said by sociologists to underlie the group mentality in the north. This is one reason I am interested in the 1718 project, which aims to re-establish links between kinsfolk who lost each other at the very beginning of the sad story of Ulster's missing cousins and siblings.