I have just been notified by simplex.com that I'm the victim of a cyber-attack.
"We wish to warn you that the following pieces of data have been leaked by the cybercriminal: name, surname, date of birth, your address, the country you live in, your citizenship, the type and number of the document you provided to use to verify your identity."
Actually there’s some security reasons why. An iCloud id have muliple purposes in the Apple ecosystem. You can use it like an e-mail address or caller/messaging contact id. Now imagine if they will free up your username and later someone else will register it. Or worst, you used that e-mail address to register in some other services.