The bun foot is one of those details that looks like styling and is actually engineering. A turned ball, slightly flattened, spreads the load of a bed corner over a wider footprint than a tapered leg does, and it puts the bearing point directly under the joint rather than out at the end of a slender shaft. On a heavy carved bed that matters: bun feet are why the frame sits solid on an uneven floor instead of rocking.
They also change the proportion. A bed on tall legs looks lighter and reads as furniture standing in a room; a bed on bun feet sits low and reads as something settled into it. Given how much visual weight a carved headboard carries, sitting the frame low is what keeps the whole piece balanced.
Our master Indian artisans turn each foot individually and then carve the collar above it by hand, which is why the four match without being identical - and why they can be made taller or shorter to suit the mattress height you are working with.