Inclined orbits precess , or change their orientation. Very quickly, an inclined ring will soon degenerate into swarms of particles with different orbital planes. The requirement to orbit in the equatorial plane of the planet means that rings are always extremely flat. Because all the ringed planets have numerous large satellites, the orbits of ring particles are constantly being disturbed. Thus collisions must still occur.
Rings are dynamic and probably short-lived in geologic terms.
At other times in Solar System history, perhaps Jupiter or Neptune had the grand ring system and Saturn's was skimpy or absent. Some mechanism must be maintaining the sharp edges of observed rings. Resonances result when two celestial objects interact with each other gravitationally at regular intervals. Lock the two objects in step so they repeat the same patterns of movement. Perturb one or both bodies enough to break up the resonance.