If you look at the platformer games, they work better with
a flat collision Hull on the floor.
So the units dont fall off the cliff unexpectitly, but
exactly when the Cliff-Hull and Entity-Hull dont match anymore.
With elipsoid Hulls, the entity probably slide down when getting close to the edge.
A flat bottom hull trace is often required, not only for platformers. A flat hull is just a special case of an ellipsoid. You can easily make the hull a flat disk by setting min_z and max_z tight together.
