Products for People.
DFM, DFA, DFX? Design and engineering share the same motivation; they're solving a problem. Though the problems vary, the approach is surprisingly singular. For me, I can't deem a problem solved until until I'm confident it answers three questions in the affirmative: Is it safe? Is it realistic? Is it pleasant?
Safe and realistic are measurable. Pleasant, however, is the tricky one, but ultimately it's the one that separates those who can do this from the ones that were made to do this. Design, at its fullest, is knowing that the operative question is not "design for what", but design for whom?