The problem is that adding so many bits to IPv6 addresses, by way of intended integration of the EUI / MAC address in particular is not actually necessary and is a bit of a mistake. As a rule, no one even wants their MAC address propagated across the entire Internet, nor to be registered in DNS either.

There are some technical advantages to doing things that way of course, but they are arguably rather outweighed by the administrative disadvantages. The protocol could have been designed so that typical layer 3 addresses were not much longer, nor harder to type or remember than IPv4 addresses are.