Such as? When we are talking about tropes, local stories (meaning what, a city? A province? What is local?) we are talking about things which transcend personal experience and are more generally known to provide a framework of general understanding.
Cat People are just Cats??
The argument is that Animal People, have tropes that are just their animal behaviors on a humanoid?
Whats a Dragonkin's Tropes? Teifling?
Honestly, asking, as that (to bring it back to the OP) is the appeal of 'Tolkien Races'. They are an established point of grounding, that near anyone who has dipped their toes into fantasy at any level, understand. It improves the shared experience, and provides a sense of world building that has already been done, while providing a coherent framework.
Dragonkin and the rest? Don't have nearly the same impact.