User blog comment:Cdswalkthrough/Vinsmoke Sanji or Just Sanji/@comment-28362353-20180505164112/@comment-25501246-20180505165700

Pretty much. This is not like Franky. The world knows him as "Franky", and those that know his real name are few.

Whether Sanji likes or dislikes his name seems irrelevant, as that won't stop the world from referring to him as "Vinsmoke Sanji of the Germa 66".

Character names should be analyzed in a case-by-case basis, due to all the special circumstances that can surround them. Trafalgar D. Water Law, for example, is known by the world as just "Trafalgar Law", but we use his full name because the "D" part is important and the fact that he's technically not using a new name so much as just omitting parts of it.