Refurbished Apple products are generally in almost indistinguishable condition from new, and are thus likely in better condition than a device you bring for repair months or years into using it. Using refurbished devices to replace used devices is a surefire way to "reduce, reuse, recycle" (especially considering that refurbishing also re-uses any returns Apple receives).
These are all good arguments, but that does not absolve Apple from the responsibility of checking that their refurbished products are not registered to a different ID. That device never should have been accepted for a return, let alone shipped to a different customer.
