You can enable these interfaces if you want. Most have very specific usage options and many people will never want to use them, but they sure can be useful.
Usually an interface is launched as the primary interface (vlc --intf interfacemodule). However you can also launch more than one interface: vlc --intf wx --extraintf sap,telnet,http
This will launch VLC with the default wxWidgets interface, but will also launch the sap, telnet and web interface in addition to the wxWidgets one.