Inefficiency basically. Burn more fuel for the amount of work output, because of heavier parts, simpler designs, less magic. I prefer such things so I am not d

Inefficiency basically. Burn more fuel for the amount of work output, because of heavier parts, simpler designs, less magic. I prefer such things so I am not damning them for this, it just is the unfortunate reality. It's a trade-off. A simple example is adding a turbo increases both power and efficiency, at the cost of more parts, shorter mtbf, and less robustness. Ie aside from just more parts to wear out sooner, the system is less rugged even when new and perfect, more easily incapacitated by a spec of dust, in a machine that doesn't live in a chip fab clean room.