Recordings provide irrefutable proof of what happened -- who said what, when, where, and how. Any person/organization that refuses to work under those circumstances gives the impression that they are not dealing in good faith.

There's a thread on here full of people who say AMEX told them one thing about sign-up bonuses over the phone, only to have something else happen to their account down the road. Wonder how many of those people wish they had recorded the call?