I think it comes from wanting to do things "right." Sloppy design is highly visible and frustrating to an engineer (hardware or software), and we want to avoid

I think it comes from wanting to do things "right." Sloppy design is highly visible and frustrating to an engineer (hardware or software), and we want to avoid that. It takes some more experience to realize that hyperfocusing on a single optimization misses the big picture and hurts other important factors.