We were doing this (and still do run our own XMPP servers for other purposes), and opted for grove for the logging, availability and to ease the maintenance burden.
Just because anyone can do it, doesn't mean everyone wants to, even (or especially) when you're a highly tech-centric organisation.
Yeah I run my own IRC server but when it came to my clients, I didn't want to be responsible for that. Grove is fantastic but wasn't all that reliable. I wish it had taken off, though! I might be forced to fill the void ;)
Just because anyone can do it, doesn't mean everyone wants to, even (or especially) when you're a highly tech-centric organisation.