What is the "message" that the Rabbi hears in it? I would be glad if I could find meaning in the custom and preserve it.

If you'd be happy to observe it, then what's the problem? It is meant to arouse a person to repentance and to cast his sins off himself. The symbolism is intended only to help awaken us.

The water symbolizes drowning and making sins disappear. Ramchal explains the idea of Tashlikh this way in Ma'amar HaChokhmah: "Indeed, since it is always fitting to make use of matters from this world for the sake of praise before Him, may He be blessed, in accordance with what is hinted at from the mysteries of His wisdom, may He be blessed, in the form of these beings and their laws, therefore people go to the water, which by its form shows the idea of things sinking into it, and points to one of the secrets of His blessed governance: that He submerges and removes evil from His creatures in such a way that no trace at all remains, as the prophet himself explains in his words: 'And You will cast all their sins into the depths of the sea,' etc." Someone who cannot connect to such a beautiful symbolic custom would be better off not eating apple in honey either, not dipping his bread in salt, not wrapping himself in a tallit, and so on and so on—customs built on the principle of symbolism. For such a person, it would be better not only to refrain from saying Tashlikh, but to throw himself out of the synagogue and leave us in peace.

Isaac, I apologize for the offensive wording. When I wrote it I didn't think it might come across as directed at you. It wasn't aimed at you personally at all. Happy New Year.