Brenderous on "[Plugin: Edit Author Slug] You should be able to set a default choice"

It's great that you can set each author's slug on their edit page, but you should be able to set the default for all new users. For example, I'd like their slug to be firstname-lastname for all new users, and not have to go and change each one every time, or do a bulk update.

https://wordpress.org/plugins/edit-author-slug/