Thank you for all the research put into this response! In some ways the Meiji-inspired scramble of renaming reminds me of Das Patent über die Judennamen and subsequent legislation about standardizing and formalizing family names.

My impression in general is that, because record-keeping was not yet totally standardized, it was done more often and more easily; also that, because social class, position, etc., were hugely in flux, people, women included, changed their names to put a period to their former lives and/or announce their stance on their new ones -- this all makes complete sense!