There is a plethora of elliptic curves that are close to the 256-bit security level (i.e., fields and groups of approximately 512 bits). Examples are Curve448, P-521, Brainpool-P512.
The standard rationale for 256-bit symmetric ciphers is to protect against Grover's algorithm, which would halve the security level. However, in such a post-quantum setting, Shor's algorithm would destroy both 256-bit curves (with 128 bit security, e.g. Curve25519 or P-256) and 512-bit curves.
In the pre-quantum setting, breaking 128 bit security is most probably out of reach for mankind, and 256 bit security is astronomically further away.
Seemingly, neither post-quantum nor pre-quantum worlds have any benefit to using elliptic curves that achieve more than the standard 128 bit security level, then what is the point of their existence and their standardization?