There is no special use case other than a dedicated
node ID.
The purpose is a a concensus node ID which should ease on
interoperability betweeen systems.
Suppose project Betula (links directory system) adds intergration with
XMPP PubSub, and choses "betula" as node ID.
Normally I would expect node id to either be random (such as a UUIDv4) or
user selected. Along with a user selected title which is usually what a
users will see when browsing.