Yes, there is a need to do this if you are upgrading your PC/laptop from Windows 7/8 to Windows 10. So why there is a need to extend the System Reserved partition. Whenever you try to extend it in the disk management console then you will find that the ' Extend' option is greyed out. The main problem with this partition is that it can't be extended easily. The System Reserved partition acquires 100 MB space on Windows 7, 350 MB on Windows 8, and 500 MB on Windows 10.
If you want to use the BitLocker drive encryption then it can only be done with a System Reserved partition as it will contain necessary files to load the encrypted system drive.
Another use of System Reserved partition is with BitLocker drive encryption. The bootloader is booted which starts the Windows OS from the main system drive. Whenever you start your computer the boot manager gets started and reads the boot data from this partition. It stores the boot configuration and boot manager data. This partition contains necessary files to start your computer. A System Reserved partition is a Windows partition that is created when you clean install Windows 7/8/10.
