a feature of UUID PKs is to allow merging of groups of records. Say there were 1000 records from an old backup that need to get into the database because they were left out/forgotten for some reason. Doing an insert will just work. If both tables started with integer keys, you've got a mess trying to move/renumber the keys of the new records. Drop them you say and let the db make new ones? Sure but now you've just suggested throwing away the primary key! Seems like a poor feature for a PK and impossible to do if existing records reference it.