WikiTree's naming convention is developed to show each person's name in different ways depending on the context. For women, this can get a bit complicated:
1. Everyone is categorized by their birthname in their WikiTree ID.
2. On their profile page, the name at the top is the name that they were most commonly known by. (For example, if you had an ancestor named Elizabeth Smith, but her preferred name was Lizzie, and she married a John Jones, the name at the top of the page would be Lizzie Jones.)
3. The profile page shows each person by all of their known names. Elizabeth Smith would show up as "Elizabeth (Lizzie) Jones, formerly Smith."
4. Female ancestors are still shown by their birth names on traditional family trees and Ahnentafel.
5. Female ancestors are searchable by both birth and married names.
You can choose to have women shown only by their birth name by using it as her "Current last name", but that isn't recommended. By listing female ancestors by both names, it makes it easier for people using the Internet to search for ancestors to find them. If I know that my great grandparents are John and Lizzie Jones, but have no idea about her birth name, I still have a chance of finding her by using Google to search for something like "Lizzie Jones died 1947 Boston."