I would say the most important requirement is customer centric design. The new pack designer should feel the product like consumer, think like a marketer, plan like a scientist and Engineer and conceive the final benefits to the bottom line like the business owner..
After that comes the holistic development of the new product which ensures cost effective solution, which takes good care of structural design, label and graphics requirements, Engineering, operational convenience, technology, sustainability, manufacturing ease and so on..
Once you can do that, the new pack designer job is easy
, no wonders ladies become better new product developers..., as definitely ladies are better in multi- tasking...