Before doing an upgrade I do two things. A full system image backup and a separate backup of my data. You never know when something may be wrong with computers.
Over the past year most computers have upgraded with minor issues that can be resolved. Things like incompatible programs that leaves remnants that then have to be removed manually. A few computer have not been able to be upgraded. The worst was recently. It was a HP8100. After installing Windows 10 the video card driver, USB driver and Ethernet driver all didn't work. Very difficult to work with a computer when so many things didn't work. Worse was HP did not provide any new drivers for Windows 10. The outcome was a restore to Windows 7. So the upgrade doesn't always work, but probably around 90% of the time it does.
Is it a big deal if you don't upgrade. Not really. The computer you have will continue to last for some years and when you're ready you can then update your computer and operating system. Whether you upgrade or not is based on your own needs and desires. I personally would lean towards upgrading particularly if you have a Windows 8/8.1 system. Windows 8/81 will end up being like Windows Vista. The operating system people preferred to skip.
Good luck if you decide to upgrade.