I've done Many applications where EDM, either Wire or "Sinker", were the Best (only) way to go.
It is by No Means an inexpensive way to Remove material. Or a Fast process. But there are times when it would be Very Difficult to achieve what you want via "Hard Machining" techniques.
EDM can also be Very Attractive when High Degrees of Surface Finish must be maintained. Such as in Mold/Die Making. Or in Medical Applications.