If IV is sent/shared with the cipher text then where is the need to randomise the IV?
Randomizing the IV makes it so that you can send the same plaintext twice, and still get different ciphertext. If you don't do that, an adversary will be able to tell whether or not two messages are identical. This can provide a way for an adversary to infer the contents of messages without actually directly attacking the cipher.

A randomized IV prevents this, even though the IV itself is typically made public, since there's no way an attacker can use the transmitted IV to decipher the message without also knowing the key.

It's a lot like salting passwords, really.