Q. Why is it that only the wives of Lemech are named? There must have been other women, so why is this the exception?
A. No one has a hard and fast answer to this. But I do have an opinion -- my speculation, and you judge it if seems reasonable. Reference, Genesis 4:19-22.
In all our history we tend to hold up names of great accomplishment by recording them or building something to them, giving honor. This goes for those who are the first to do something, like being the first to fly around the world, or the first woman to vote, etc. We are told that Lamech had two wives, Adah and Zillah. Adah means, ornament, while Zillah means nothing, only the name of a woman pre diluvial. Perhaps Adah was the first trophy wife? Just kidding, but maybe true. There is only one other woman named during this time, other than Eve, the mother of all, and that is the sister of Tubal-cain, Naama. My reasoning is that these women are named as the first of something and that first, I believe is why their names are given. Lamech's two wives? Perhaps the first two women to be married to one man. Their mark to fame may have been they were the first two women to share a husband. Next, the sister of Tubal-cain is recorded for all history, and what does her name mean? Nothing, only that she is a woman who lived before the great flood. So, what would be her mark to fame? I believe it is that she is the first woman to marry her own brother.
Of course these firsts would settle, destroy really, all of the speculations about who the children of Adam and Eve married, and would give a better understanding of Genesis 6:1-4, where we are told that the sons of god took wives from among men. The Gods being those of Adam an Eve and the wives of men those from the land of Nod, or the land of the wanders. See also (Cains Wives).