My reason for learning the backcast, is simple weight. Have yet to see anyone pendulum a 10oz. lead and a chunk of bait. I have seen it done with a backcast, and easily. Have done it myself.
Both styles are fine if you are away from people when on the beach fishing. In a crowd, no way both too dangerous. My reason for learning the cast was the same heavy weights and bait can be thrown, and I do not fish crowds here on Hatteras.
In the Uk the backcast originated in the east anglia region and thats where the heavy hitters come from. David Vicary taught me and I have yet to see anyone top him at his style of casting.
Not as fluid and stylish as the pendulum, but it gets the job done when the pendulum physically cannot do it.