One of the major areas of epidemiology is discovering the evolution of the virus. Using this information they can predict where other outbreaks might appear. They can identify existing breakouts, identify how it is spreading and then make educated predictions about which areas are likely areas of new breakouts. This isn't directly related to the development, but of deployment, which in a world of limited resources is very important.
While we cannot predict which mutations virii will undergo in the future, we can make predictions about which extant virii might become the predominant virii using the theory of evolution - which is useful in developing future vaccines. The theory of evolution includes explaining how migration can alter gene frequencies - a vital piece of knowledge for vaccine development and deployment.
The central fallacy though is this:
It is a useless theory... that has essentially contributed virtually nothing to empirical science. It can not predict what, where, or when a mutation will occur.
If a theory has no use, then it is useless. However the theory of evolution has uses. It certainly can't predict chance events, though genetics has lead us to 'mutation hotspots' which are more likely to mutate than others.
I will tell you one contribution to empirical science right here: Genetics. The theory of evolution demanded that (ie predicted that) there should be some unit of heredity. Since the theory had withstood its first trial by fire, it inspired scientists to go looking for genes. Without the ToE it might have taken us some time to figure that out so the ToE has advanced modern science in a gigantic way just by doing that.
As you state:
Beyond that, there is no utility to the theory when developing vaccines.
You even concede that it has
some utility - even if you only see it as a minor use. I assure you that epidemiologists - the guys that do this for a living - do not think that knowledge is only of minor consequence to saving lives.
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