Board Thread:Character Discussion/@comment-34924658-20161007024033/@comment-25375217-20161007033739

In the past, by my (admittedly weak) understanding, surnames only existed for the sake of family pride to make sure that ancestors are always remembered. Cora is obviously a very prideful woman, so she would take a last name so that her children would always be known as the children of Cora Mills/Miller. The Lucas family also appears to be pretty well off, so they would reasonably have a surname as well.

Rumplestiltskin, on the other hand, is the child of a scoundrel. There's no family pride there, and he certainly would not want to take a name that would keep him attached to Malcolm for his entire life. Perhaps the spinsters, but even they seem to be rather poor.