Is it only because of the less friction involved or at there other reasons?
Movements under gravitational acceleration requires shifting of center of the mass. Any object stays at rest on the horizontal plane will have it's center of mass within the walls of its footprint.
A cube will lose this stability only when one of its side is lifted above 45degree angle. Only above that angle the center of mass of the cube will go outside of its footprint, thus fall on its side.
But for a sphere, its footprint is a tiny point on the horizontal plane. Thus any slight push on it's side will shift the center of the mass outside of the footprint and makes it to roll.