IPv6 had this cool idea that each subscriber would get a /64, and devices within the subscriber's network would be assigned /128s with the last 64 bits matching their MAC addresses.
Except it turns out that most organizations see no need to give internal devices globally routable IP addresses, much less expose their MAC addresses. If anything, it's a vulnerability, not a feature.
On the other hand, going too far along with your idea would look like a dystopian future where everyone is corralled into one corporate walled garden or another. So it's understandable that there's a strong gut reaction against it. Fortunately, there are enough IPv4 addresses to support both corporate walled gardens and a reasonable number of independent operators.
Except it turns out that most organizations see no need to give internal devices globally routable IP addresses, much less expose their MAC addresses. If anything, it's a vulnerability, not a feature.
On the other hand, going too far along with your idea would look like a dystopian future where everyone is corralled into one corporate walled garden or another. So it's understandable that there's a strong gut reaction against it. Fortunately, there are enough IPv4 addresses to support both corporate walled gardens and a reasonable number of independent operators.