Oda already does. Several times.
What is stopping you to accept the title for what it is, is what it means powerscalling wise for Mihawk/Saint Shanks/Roger.
For example if Saint Shanks was the WSS do you think that people would act as if they don’t understand how the title works? No, they would say that Saint Shanks is stronger than any swordsmen, period. The same way they have no qualms saying that he has the strongest Haki even if he has no title backing that up.
The only issue here is the unwillingness to accept that Mihawk > Saint Shanks.