The older women, who are the subject of part of this thread did have 'normal' names, and from this distance it is a bit difficult to see why they changed them. It may have been a whim, or a reason now forgotten. Certainly my younger friend who changed her name had one that seemed reasonably common. It was at the time she decided, associated strongly with a slightly annoying, and now forgotten celebrity.
I did meet someone whose family stopped calling her by her given name of Ethel after the Crippen case, although it is, interestingly, not a name that has returned.
Many of us will remember Myras who changed their names, and I know one whose family decided to keep it.