I think that's the way it should be. This is an epic story spanning the whole of known space at the time. It would be too narrow a focus if it were strictly about the NX-01 crew. It's not an Enterprise novel in the sense that it's about NX-01, period; it's an Enterprise novel in the sense that it follows many characters established over the course of the television series of that name -- Hernandez, Shran, Soval, T'Pau, Kuvak, Samuels, Gral, Thoris, Gannet Brooks, Valdore, etc. -- and explores the roles they played in this sweeping historical event. This book only covers the first year of the war. There are five years left before the UFP is founded. And remember, just five years before this, the Vulcans, Andorians, and Tellarites were at each other's throats and none of them had any use for humans. So things can change a lot in that time.