What is their role since they're not used for confidentiality reasons?
IBAN (International Bank Account Number) is the system used by bog-standard banks for transferring between accounts.
Ethereum has ICAP (Inter-exchange Client Address Protocol), which is effectively a decentralised version of IBAN.
From the glossary in the Homestead guide:
ICAP Interexchange Client Address Protocol, an IBAN-compatible system for referencing and transacting to client accounts aimed to streamline the process of transferring funds, worry-free between exchanges and, ultimately, making KYC and AML concerns a thing of the past.
There's some further information under Your First Account in this guide.