IPv6 provides an address for each node on the Internet. So NAT has no more use for address depletion.
NAT also provides some basic security. But NAT as any stateful device can also be the target for DoS attacks. And any NAT device within a network provides an easily exploited opportunity for undetected Man In The Middle (MITM) attacks. Only End-to-End security offers protection from exploits related with ARP or ND+MLD where End-to-End security is likely only possible with IPv6. This does not need to be IPsec.
A RFC was written to explain how to get the security benefits provided by NAT without NAT.
This is rfc4864 Local Node Protection