This has been a very interesting read. I grew up on the opposite side of the country from my parents' siblings, so there were no cousins, aunts, uncles or grandparents in my life. I greatly regretted this. It was in a time when people did not hop a flight to visit family. Long distance calls were so expensive they were almost never made.
However, I have a theory about family closeness that others may or may not agree with. From my experience women are primarily, not always, but primarily the ones interested in close family ties. All six of my parents' siblings were men, and in my mind, that didn't make for a lot of keeping in touch. I have two sons, and two stepsons and I find that I am the one who makes all of the contacts for family get togethers. Again, I realize some others have had different family experiences.
Also, there seems to be one, maybe two, people in a family that are willing to take the emotional risk and time to keep the family together. In my husband's family it was me and my MIL. When she passed I couldn't do it alone, not enough response.
Just my experience with family and closeness.