IIRC FAT32 supported larger sectors in part for future proofing. It was made because of storage length limits on its predecessor so it makes sense that the devs were very conscious of the need.

Also some storage systems are more efficient speed-wise with larger sectors (though if that was a concern for you, you probably weren't using FAT<anything>). It also made switching between 16 & 32 in-place easier, though I can think of a reason off the top of my head why you would want/need to, and none of the standard tooling could do that.