Unit load devices (e.g. an LD3) have standardized dimensions, so you don't get much by having a taller cargo hold than any other widebody. At best you want to

Unit load devices (e.g. an LD3) have standardized dimensions, so you don't get much by having a taller cargo hold than any other widebody. At best you want to ensure that a person can stand up (or mostly stand up) in the cargo hold as it makes operations easier.