You don't have to remove negotiation and complexity from the system when it's used for data. My question isn't why those systems are there so much as why they are needed for the charging use case. E.g.: why do chargers even need more pins wired than +5V and ground? Is there really such a large benefit from making chargers "smart"?
That doesn’t mean you can remove the microphone.
Optimising the common case in this instance will remove all other possibilities.