There is nothing insecure in a protocol by itself. In this case, since it lacks encryption, it shouldn't be used over insecure networks such as the Internet on

There is nothing insecure in a protocol by itself. In this case, since it lacks encryption, it shouldn't be used over insecure networks such as the Internet on its own. But it's by no means the only way it's being used. There is a place for FTP, Telnet, TFTP and many other basic protocols - it all depends on how you use them. The only thing that Apple gained by this is that people will use third-party FTP clients (which might be good given Apple's recent lack of focus on security anyway.)