Two things come to mind:
Paths, things in the user.lib (or vi.lib/instr.lib) have an aboslute path, moving a VI that uses one of those functions isn't going to force a re-linking. This means I can have my code under SCC in d:\sourcecode, my colleague can have it on his USB-drive at f:\code. Which also means it's easier to setup a coherent IDE, just install the packages in a manner you like (copy, VIPM, install with NI installer) and you have them where you expect them
QuickDrop The items show up in a quick drop search (which can be very usefull)
The other advantage is the thing you allready mentioned but (IMHO) is very important, you can easily access them. It's possible to browse them through the palettes. In some of these dying seconds of the day (when the coffee isn't ready yet, a download is going on, facebook is offline, whatever) you can go through them and see if any of your colleagues has writing a little gem, he mentioned but you weren't listening.
Ton