Why just Halflings? Or why specifically halfings?
I guess this confuses me. There have been a few threads like this recently.
Why isn't the same true of Dwarves? Is there anything more cliched and dull than a D&D dwarf? What about elves? They are not Tolkien's immortal beings full of grace, or strange fell fey creatures from the lands of faerie, they're just humans with pointy ears who live a long time and spend that long time hanging out in forests and practising archery.
It's not that I can't see why people might find Halflnigs boring. I just don't see why there is a problem here exclusive to them.
Okay, so let us start with the really basic stuff.
Dwarves live in the Mountains. That immediately makes a difference, as stupid as it sounds, because Dwarves live "over there". And it immediately starts raising questions. How do they handle this problem in the mountains, how do they handle that problem. It also raises the question of how they interact with other races. Because they live in the mountains, it opens that door and gives us an option. Are they friendly with their neighbors, or not? And beyond just living in the Mountains, they tend to live underground in the mountains. This opens up even more potential.
So, as a world-builder, just this single simple meaningless fact gives me a lot of options already. I have to start thinking about how they live underground, how they get food, how they interact with their neighbors. It seems like it should be a fact that doesn't even matter, but it starts shaping a lot of how you can present the race. Making them stoic warriors in grey and icy fortresses far up in the mountains who isolate themselves from their neighbors is an option, as well as merry craftsmen who send trade delegations from their mining homes constantly to their good neighbors.
The craftsmen part is also important. Dwarves forge, and traditionally they are one of the best. This gives us angles to work with. Some lore has them enlsaved for their crafting ability and recently freed. Some lore has them having the best troops, because they have the best equipment. Some lore has their skill translate into vast wealth for their nations. And you can turn this dial a few different ways. For example, I once had a set piece location that was a dwarven super forge that used lava and the heat of the core of the planet to forge things like adamantium. We start asking, how do they make that. Why do they make that.
But, one of the biggest things I've seen with Dwarves that gets played with more than anything else, are the clans. Out of every race in the game, the only other one that gets close to this I've seen are orcish tribes. A dwarven clan gives us a unit to manipulate. If your clan is the clan most known for the warriors who guard the borders, that clan is very different than the clan most known for making beautiful jewelry, or for caring for the dead.
The clan allows us to take the dwarven society and chunk it up. Every dwarf is like this, but Clan Gem-Eye is also that. And by making these divisions, you can start piecing together a more complicated relationship. You can have rivalries, wars, different factions with different goals. And, it also allows the character to work with a new unit. Maybe your character is not in a good relationship with their clan, but they are with their family. It allows you to play with this extra layer.
Now, to turn this back around to halflings for a second... they live with humans. Basically all of the things we discussed in the Mountain part of dwarves for halflings is just "copy the humans". What do halflings do? They are simple farming folk. Maybe tavern owners or shopkeeps. In the worldbuilding sense... they are a pallet swap. You'll never go to a halfling city. The best you can do is a small halfling farming village... which is just a farming village. But a dwarven city is very different from an elven city is quite different from a human city.
Where in the world building sense I can see dwarves having multiple dials I can spin... halfling dials are all set. They don't move. And that is why I think things like dwarves and elves end up more interesting, because we can adjust them more, where as halflings... don't really change.