My question maybe will be stupid, but my problem is that I do not understand why stream ciphers need a key and also a nonce. As far as I understand, the keystream is generated with the nonce. The same key can be reused with a different nonce.
Wouldn't be simpler just to use a new key each time? If I understand good, to decrypt the message the recipient needs the nonce. Is communicating the nonce simpler than communicating the key?