There are only two types of euros: notes that are physical evidence of said money, and deposits in banks. You can transact by exchanging notes or by instructing your bank to perform a transfer. Both have limitations with the second being that you have to involve banks in the transaction and have a bank account, etc.

Digital currency has all the benefits of both methods with none of the drawbacks. No bank account required, no banks required (other than the ECB, but they are also required for bank notes), instant exchange, privacy, in person or distant transactions, etc.