Two major impact areas for product development engineers.
Designing new products is a very tough job; there is so much to do and little time to make it happen. Speaking specifically about molded plastic parts, four critical areas usually blend together in successful product designs. The 3D part design, material selection, tool design / construction, and simulation /processing. If not impossible, it would be extremely difficult to find any one person who can do it all. This is why it is so important to have molding partners that can help share the weight of the new product development process.