Speed. Ramps.
With high-frame-rate input, we can achieve beautiful, fluid speed ramps. The output standard-frame-rate footage can have smoothly ramping speeds, just like we used to be able to do with film cameras.
And the new trick is that square wave or soft Tessive Elemental shutters can be applied evenly across the entire shot during the ramp. This means the motion will look the same even though the rate of action is changing.