One of the most important things to understand when studying history is that historical events never occur in a bubble, or rise out of nowhere. Instead, every event is connected to past ones that created the necessary conditions for the event to occur.
Historians value context so highly because it allows them to understand how the connections between all these different events work. It enables them to see patterns that make the study of history sistematic. It also allows them to imagine what the future might look like.
A broad understanding of history, and particularly an understanding of world history, is extremely important if we want to understand Western civilization. This is because the Western world has developed within a larger historical context that includes the whole world, and understanding this context allows us to understand the pressures and influences the Western world was under.