I agree that restricting access / filtering dmesg or equivalents is a good thing.
An oops highlights that something went wrong and the OS should not continue in this state. If you allow oops then an attacker might bruteforce KASLR offsets for the kernel base, have multiple attempts at an heap overflow or against a stack cookie. Many mitigations rely on the fact that the attacker have only one attempt.
Taking your example on NULL pointer deref. It can be a simple pointer not checked for NULL or a corrupted object. Not panicing leaves more room for an attacker to reliably exploit a vulnerability.