I'm ok with him being omitted from the film, but I'm glad the novel could afford more space for someone like him, a foil to the mood of impending doom, and also just plain fun. He rescued them and equipped them, and one of the weapons he supplied played a pivotal role later. Merry would not have been successful without that blade, and Tom is a believable source for such immense help. There's a book of Tolkien's letters and in letter 144 he explicitly says he intended Tom to be an enigma because he felt there should be some in the mythical age of the story.

"Old knives are long enough as swords for hobbit-people," he said. "Sharp blades are good to have, if Shire-folk go walking, east, south, or far away into dark and danger." Then he told them that these blades were forged many long years ago by Men of Westernesse: they were foes of the Dark Lord, but they were overcome by the evil king of Carn Dûm in the Land of Angmar.

"Few now remember them," Tom murmured...

https://tolkiengateway.net/wiki/Letter_144

https://tolkiengateway.net/wiki/Letter_153

https://tolkienessays.com/tom.html

I don't disagree with him not being in the film. (Perhaps more controversially, I think the scouring of the Shire properly appropriately didn't belong there either.) Great as The Lord of the Rings is, IMO it has structural problems as books.

But I don't really disagree with your comment in general.