Reason certain Old Testament books are only canonical in non-Protestant Bibles

[Greedo punched first]

What is the reason books like Judith, 1 Maccabees, 2 Maccabees, and Wisdom of Solomon are only canonical in certain non-Protestant Bibles?

[The Mikado]

They were not in the accepted Hebrew Bible (Tanakh) used by Jews, but were introduced in the Septuagint, the first translation of the Bible from Hebrew into Greek in the 2nd century BCE. When Saint Jerome eventually translated the Bible into Latin (the Latin Vulgate, the base of the Bible the Roman Catholic Church uses to this day), he translated the Old Testament based on the Greek version rather than the Hebrew version. The "problem" of these books was really showcased in the 16th century in the Polyglot Bible, a Bible that had the Latin text, Greek text, and (for the Old Testament) Hebrew text side by side. Later, Protestants translated their Bibles' Old Testaments directly from the Hebrew and omitted those books, and they became associated with the Catholic Church in Europe (so, for example, the story of Judith slaying Holofernes was something that might be celebrated in a Catholic stained-glass window, but no Judith for you, austere Reformed church).

As you note, the Eastern Orthodox Church has an even wider Old Testament, and the Ethiopian Orthodox Church has the widest still.