There is a particularly foolish article about baby names at The Daily Beast. (I know. I followed a link from a usually trustworthy source. Really.) The author is described as a "baby name expert." Sez who?
For hundreds of years, both boys and girls names were very stable. Girls were Mary, Anne, or Elizabeth, though Margaret, Alice, and Joan also got some play. 50% of females had one of those names. Over 50% of boys were John, Thomas, or William, with Robert and Richard in the second tier. By mid 20th C, Michael and David were perennial tops for boys, Mary, Linda, Susan, and Betty for girls. But the wheels were already turning. Girl names had more variation throughout the 20th C, but really picked up steam after WWII. The most common name changed every 15 years or so, from Mary to Lisa to Jennifer to Jessica. Now it changes every few years. The top 10 for boys in 1990 looked scarcely different from 1950, but are now starting to show the same turnover that the girls did a few decades ago.
What does it mean? Many things, and I won't even attempt to cover them all. And I will wildly overgeneralise, because we are speaking of trends, not individual decisions.
The stability of boys' names was meant to convey solidity and strength. Girls' names came to be regarded as something more decorative. In evangelical circles, Biblical names were big, so there were plenty of Rebeccas, Sarahs, and Rachels, but there was also a wide field for something more unusual. Roman Catholics insisted on a saint's name - my wife Tracy was actually baptised Therese. Paedobaptist traditions in general have been more conservative in naming. Washington Post columnist Eugene Robinson has long bemoaned the drive to unique names in the African-American community, attributing it to the breakdown of families and generational continuity. But this also results from the black churches being much less likely to practice infant baptism, a reality that long predates the last few decades of absent fathers.
More recently, parents have taken to giving their daughters some of the less-common boys' names, or English surnames with a rather aristocratic feel to them, such as Madison, Cameron, and Taylor. But far more common have been older female names, so long out of use that we cannot think of them as girls' names, but as women's names: Olivia, Sophia, Abigail, Isabella. Similarly, the new names for boys - Jacob, Alexander, Joshua, Ethan - are recognisable old names. These do not suggest continuity so much as approbation of tradition, which is somewhat different.
Families have less continuity, so it is hardly surprising that there is less of it in the names. Yet we still desire something of that hearkening back, and so pull names from the Old Testament, classical history, Victorian England, or the American West (Cody, Colt, Dakota). We are more fragmented now, and while there still are top ten names every year, those ten represent a smaller overall percentage of the total - and the published lists have moved to top 25, then 50, and now 100.
In our family, the tradition of using Douglas as a middle name has held for at least five generations on my wife's side. Naming a first son for an uncle will go to three generations on my side if the new Wyman is a boy: David-David/Jonathan-Jonathan/Benjamin-Benjamin. We have had fewer girls, so there has been less opportunity for tradition, but taking a middle name found in the family tree has some precedent. My grandaughter's middle name is Adelaide, not only her great grandmother's middle name (she hated it, BTW), but a form of her mother's name, Heidi.
It is a continuity, not so emphatic as Junior or III, but similar to the custom in many cultures of naming after a grandparent or great-grandparent.