You don't have any plans on removing DRM... And if need to remove DRM from some of your files, what will you do? It might not be that easy to downgrade your WMP. However from the security point of view it is usually a good idea to get the latest version of software.

Why do you wanna upgrade your Windows Media Player. Is your current version unstable?

Please note that after upgrading, you might need to get DRM licenses from DRM-protected videos to play them (of course DRM-free video files should play just fine).