And what other decision could he have made? What man, or rather hobbit, could step back in a situation where there might be nobody else to do it.

It's very important to remember that one of the strongest influences on Lord of the Rings was Tolkein's experiences during World War I. You didn't not go and fight. It "wasn't done."

Frodo was drafted, and chose to stay.

Sam volunteered, and Sam was every good soldier Tolkein knew, every gardener and carpenter so far from home.

People do NOT understand that Lord of the Rings is in part a war novel.