Why is MAC using nonce+message+hash(nonce+message+identifier) not the standard?
It has the disadvantages of any MAC-then-encrypt scheme, which I'm quoting from the linked answer below. In addition:


It has the property that you need both a nonce and a hash, so for equivalent security it requires more message space.
The nonce has to be random, so it requires strong random numbers for each message, unlike e.g. AES CTR + HMAC.
Doesn't work if you need deterministic encryption, for some reason.




From the link:


  Does not provide any integrity on the ciphertext, since we have no way of knowing until we decrypt the message whether it was indeed authentic or spoofed.


This means that it may allow some chosen-ciphertext attacks that encrypt-then-MAC would protect from. It also means more time is wasted on incorrect messages, which could e.g. help with denial-of-service attacks.


  If the cipher scheme is malleable it may be possible to alter the message to appear valid and have a valid MAC code. This is a theoretical point, of course, since practically speaking the MAC secret should provide protection.


In your scheme the nonce and ID take the place of the MAC secret, which could be weaker if the encryption is weak and the hash function isn't a strong MAC in that mode, but can't be any stronger. Still theoretical, as long as you choose a strong, unknown nonce.