Well, somebody better know the structure of the metals in use, or else you get turbine disks shattering jet engines and landing 1,000 yards away [1]. Just because it's not important to know every day doesn't mean you won't find challenging and important applications of undergraduate-level algorithm design.

[1]: http://www.seattletimes.com/business/boeing-aerospace/dramat...

Which it completely is, if you want to design a modern engine.

If you want to have an engine with 60s power, weight and fuel economy, then sure you don't need to know the science behind it. Just throw some parts together, and you'll get something that works.

Metal crystalline structures are taught in many metalworking trade schools, even if briefly. It has direct implications for things like heat treatment.