It was Ruy Lopez de Villalobos who named our islands in honor of the King of Spain, Philip II, then Prince of Asturias. He named them the Philippines or “las islas Felipenas“. We accepted that name and it is used internationally.
However, even major news outlets would sometimes refer to us as only Philippines omitting the “the”. The name has always been considered in the plural. It refers to a collection of islands. It is often shortened to “Filipinas”, “Pilipinas”. I believe that it is crucial to always include this article in order to refer to the collection of islands and to remind ourselves that this country is an archipelago, that it is composed of diverse peoples, and that this diversity is part of our identity.
Sometimes little details bring with them great meaning. Lose the detail, you lose the meaning.