Reason 1: people upgrade Windows 7, 8 and 8.1 to Windows 10 We know after upgrade system, there will be several drivers incompatible with windows 10, and some drivers are missing. We know some drivers are only supports some systems.
It reminds you to download and update graphic card driver or other drivers.
Reason 2: Drivers need update itself Hardware driver is also software, it is manufacturer developed to make hardware work.
Even if you're not prompted, I always recommend restarting anyway.
The driver update process involves changes to the Windows Registry and other areas of Windows.
Important: If you're installing a driver from anywhere other than the manufacturer of the hardware, click the STOP Installation button instead and obtain drivers from the manufacturer directly.