As you add more experiment with more hardware on your computer, you no doubt upgrade your components, or just lose interest in some. Windows adds drivers to items you didn't even think had drivers, like monitors and USB flash drives. It retains these records just in case you attach the device again. Even if you think you've successfully uninstalled the device, it can exist in your Windows configuration, which could cause conflicts, or just take up space.
Keeping your system as clean as possible is always a good idea, and completely removing unused drivers is a way to help your system's arteries from getting clogged with digital plaque.
Read more at OCModShop.