Knowing the historic architecture of your home can also teach you what is and isn't original to the home. Over the years, I have been a detective for homes that have been renovated, trying to find out for example what a room was originally used for, or where a door/window used to be. Finding "shadows" (as I call them), on exterior or interior walls can tell you what the trim might have looked like, and knowing the historic style of your home will help in this endeavor. Figuring out the original floor plan will be an easier task if you know the home was built as a Greek Revival, and not a Colonial Revival.
From my perspective, if an agent can't properly describe the style of your home, you might think twice about hiring them.