As I said, some don't come back. From your examples, ones that should have come back but seemed to have missed their window would be Gladys, Ethel, Phyllis, Doris and Hilda (although I know a lot of cats and cars being called Hilda!). We have seen Ettie come back hugely so perhaps parents are skipping the formality of Ethel. I am always surprised Doris isn't bigger, it has a lovely sound and meaning and diminutives that sit with modern trends (Dorrie, Dory, Rissie).
Elsie is huge - number 19 in the 2021 stats and it has been in the top 200 since 2018. Vera is also rising fast, up 700 places in the last 8 years or so, likewise Winifred and especially Winnie which is just outside the top 200.
We are slightly ahead of times with Irene, Jean, Doreen and Brenda, all peaked in the mid to late 1930s. And Barbara, Patricia and Sheila are firmly 1940s names so I am expecting grandchildren with those names (and perhaps Roger and Brian for a boy😬).
I think we possibly see more name extinctions due to more creative naming trends nowadays. There is a much wider pool of names in use so what is in the top 10 now doesn't have the same amount of children born as it did 10, 20, 30 years ago. It is much easier to have a slightly more unusual choice. We are also more adventurous with names, especially girl names, as well as more global. We are happy to use nicknames as given names, use words or surnames as first names and look at culture and history when considering our choices. Names now are a reflection of who the parents are - their tastes, their culture, their background - not just a method of distinguishing someone from another person.