Do you think it is an oversight on Steinbeck’s part that Curley’s wife was never given a name? If not, what are some of the reasons the author might have chosen to leave this character nameless?

No, Steinbeck left Curley's wife nameless because her name wasn't important. She was the only woman in the story. It wasn't necessarily her gender that was important, but rather her status. She was a lonely woman in a man's world.... that was all we needed to know.