Imagine you are hosting a defensive siege and you live in a desert area (africa, middle east I think part of california) and you had quicksand that people could fall through. This could be great for traps and a change from the traditional slab ganks which just gurantee death. I feel like alot of updates and features are QOL or to improve gameplay function but I feel like adding quicksand would just be a fun addition to ccnet.

You could add blocks per chunk limit to prevent surrounding entire forts with it and you could make it so when its placed no slabs can be anywhere within 50 blocks of it.
I personally enjoy hole fighting the most, big trenches everyone going at it without the slabs such as when forts are bombed and everyone fights in bunkers without having to worry someones going to tickle your toes in slabs. I think quicksand would promote this and push people away from the traditional quicksand