The photographer can switch the hybrid viewfinder to EVF mode when they are using zoom lenses or lenses that are not well supported by the OVF.
For me the main interest in the Fuji system comes from the availability of OVF and a nice set of prime lenses that are designed for the APS-C sensor size and fairly compact for the focal length and aperture, which would potentially make a great camera for documentary photography at close range. Without the OVF, even though it has limitations, I'm just not interested in the system at all. I believe the X-Pro lineup of bodies are mainly designed for people with a similar mindset, i.e., those who consider the OVF important. The XT series are for those who want the best EVF and do not need a hybrid viewfinder. I think having a choice is always a good thing, and I really like Fuji for keeping the OVF available in some models.