It is not a necessary prerequisite to have more than one skin, however if you want to mix and match skins in different applications you'll probably have a hard time doing it without the help of some third-party skins. In order to fully maximize your VLC experience you should have at least one skin to use.
It can be downloaded directly from Videolan's home page. VLC media player Skins Pack is free, an ideal free software just for Windows, being a part of the multimedia category of desktop customization software.