Catch-alls are a bad idea...
Catch-all addresses attract spam, and you're either going to get fried for snooping, or fried for passing mail on to the wrong address. Even if you survive a potential frying, you've made an open-ended commitment to sorting out typos for users who won't bother to check where they're sending stuff.
They are useful as diagnostic tools though, especially when rogue users start setting up shadow IT systems and misconfigure them... Yeah yeah, this is an ancient example, so shoot me...
Me: Please shut down your Netscape Collabra server, your "intranet" is not officially sanctioned and is insecure.
Him: This matter does not concern you.
Me: Security of the campus network IS my concern. It's actually part of MY job.
Him: I still don't see why it's any of your business.
Me: Do you admit that you are running an unauthorised server on personal equipment ?
Him: I refuse to incriminate myself.
At this point, I hold up a print-out of a bounced e-mail from the offending machine, because he cocked up the configuration.
Me: Are... You... Run-ning... A... Net-scape... Coll-ab-ra... Ser-ver ?
It's a bit like that scene from Red Dwarf where Captain Hollister asks Lister about Frankenstein, but I was determined that this guy and the intranet weren't going to have a baby intranet.