I agree with you on these points, an industrial designer with knowledge of material, process and assembly is helpful to his job,“pretty picture” stereotype can not add any values on their products.
A good designer(industrial design or product design) is who can see inside of customer and know what customer wants exactly,and more important,he knows how to present customer’s idea(maybe sometimes his own idea) in visible and understanble way,and ensure it is pissible to produce.