I realize it's a joke, but even then it's not a good one. The reality is actually the other way around. Anyone can build a bridge that barely stands, but it takes an engineer to build one that still stands after an earthquake.
I'm not sure if the original designers intended for these to have multi-millenia design lives, but I bet that they could have been made much cheaper...
Precisely! Engineering usually isn't about designing the best X, it's about designing the cheapest X that meets all of its requirements.
Edit: even if the requirement is for X to be the best in the world (which, as a non-quantifiable requirement, makes me uneasy), the goal would still be to do it as cost effectively as possible.
