Where do you keep the decryption key? If it's stored in the same place as the encrypted password, then you have gained no security over storing it in plain tex

Where do you keep the decryption key? If it's stored in the same place as the encrypted password, then you have gained no security over storing it in plain text. If it's stored in a separate system, then you have substantially increased the complexity of the system, and in general, a more complex system is harder to implement securely.