I’ve heard or read several historians question whether it really matters if we correctly diagnose the plague or not? After all, everyone including the Yersinia deniers agree that a great mortality occurred. This type of question points out the gap between historians and the sciences.
I think most people in the sciences would answer ardently YES! To the sciences, diagnosing the disease is the overwhelming priority. If it can’t be diagnosed then there is no point studying it at all. Thus, all efforts are put into diagnostics until consensus emerges. Everything you can learn about the plague flows from the diagnosis or disease characterization.
The sciences also have the responsibility of dealing with a reoccurance of the plague. Medieval historians do not have a responsibility of dealing with a reoccurance of their study subject in the modern world. Medievalists who prefer to keep the identity of the plague a mystery (so the can write whatever they want about it) clearly are not worried about responding to its reoccurance in their community today.
On top of understanding the historical plagues, millions of dollars are spent every year on plague preparedness, response and research by governments, the World Health Organization, and others. Your tax dollars fund this work. Governments spend this money because they believe that Yersinia pestis is capable of erupting into an outbreak as it did during the first two pandemics. Beyond natural outbreaks, we know that it has been used as a biological weapon as recently as World War II with the intent of creating death and social disruption. It did successfully create local epidemics in China. We don’t know more about it because the West is terribly uninformed about the Japanese-Chinese front in World War II. Biological weapons used by Japan on China during WWII are one of the primary reasons China has such tense relations with Japan to this day.