Re: We didn't run out of ipv4
It allows you to use your MAC address (48 bit) as the address on your /64 network...
No need for DHCPv6.
Yes, it would be nice if you subnet your /64 network - but not mandatory.
Sigh...you don't use your MAC address as your IPv6 address. It can form the basis of an IPv6 address using EUI-64. Definitely not the same thing.
Regarding DHCP, are you planning to just continue to run your DHCPv4 servers? If not, every host will not receive autoconfiguration for all of those lovely DHCP options not covered by SLAAC (e.g. DNS, WPAD, PXEboot, etc.). DHCPv6 fills in that gap if the plan requires completely dismantling the IPv4 infrastructure.
Anyone who thinks we'll be completely off IPv4 anytime in the next 40 years is trying to sell you something.