Think about it this way:
* "Board games" emphasizes the use of a physical board as a core component. This distinguishes them from card games, dice games, or other types of games without a board.
* "Games" simply signifies that these are activities intended for entertainment and usually involve rules, competition, and/or chance.
So, "board games" is a descriptive term that tells us exactly what kind of game we're dealing with. It's like saying "soccer ball" or "tennis racket." It's a specific type of something within a larger category.
Without the word "games," we might end up with ambiguous terms like "boards" or "board things."