Right now you have to set Carrier/Service/Package all together in a shipping preset as a shipping rule. However, often the criteria for these three pieces of information are entirely different. Right now you would have to write a rule for every possible combination. Instead I would like to be able to set Carrier/Service with one rule and Package with another. For instance right now I determine Carrier/Service based on shipping zones and requested service, and I determine package based on weight and order quantity. If I were able to uncouple these, my number of shipping rules would be cut in half.