The point is to renew the core signing key, encryption key, and authentication key, and to create a set of subkeys to be used on devices without access to the GPG card.
The encryption key should not 'expire' ever, as it is needed for communication, the same is true for the parent key, which should never be anywhere other than the card and the veracrypt container. We give them an expiration date anyway, so that if something happens and I can't renew them, they eventually become invalud.