Historians who refuse to engage with counterfactuals miss an opportunity to talk about history in a way that makes intuitive sense to non-historians, while introducing theories about evidence, causality and contingency into the mix.
The best characteristic of well-done counterfactuals might, in fact, be the way that they make the artfulness inherent in writing history more evident. After all, even the most careful scholar or author employs some kind of selective process in coming up with a narrative, a set of questions or an argument.