Working for a crane manufacturing company. While raw material costs are maybe not that drastic, we consider material efficiency the most important metric for cost and a lot of brain power was spent to optimise the amount of steel used. There are multiple reasons for this. The ones I can think of are:

  * The margins for cranes are thin and steel is expensive.
  * Thicker steel is harder to work with, increasing manufacturing cost.
  * Each kg of dead weight may decrease the performance of your product, e.g. max. Live load. This is especially true for the jib.
  * More weight at the top of the crane may necessitate a sturdier structure below, amplifying cost even more.
  * More weight may require more ballast blocks, which are costly (especially transport)
  * More weight means higher transport costs
  * More weight means more wind area, which is the critical factor for high constructions.