There is a key person in any complex project: the coordinator, or project manager or chief engineer.
He/she is who coordinates the strokes of all the other designers in order to achieve an harmonized effort that renders an expected profit for the group.
He/she has to consider many factors of production, competition, sales and product support.
Among those there are economy of material and work, cost of machines and processes, market demands, budget restrictions, etc.
He/she must make compromises, some things are sacrificed in order to achieve other.
It seems to me that in any evaluation of cost of production versus potential of sales, the post-sale difficulty of maintenance or service is not among the strongest priorities, especially if equivalent products of the competition are not much better about that.
http://engineerexplains.com/answr/Screw-vs-Bolt1.html
