The original orbits would take ~100 years to decay, which is way longer than the life of the satellite. The new orbit is around 5 years (not taking into account maneuvers from the fuel on board). Makes a lot of sense, especially since it looks like they'll be iterating the design as they go (two that jumped out at me: initially not all satellites will be taking advantage of both Ku and Ka bands, and not all satellites will have phased array antennas)