Everything, absolutely everything needs maintenance. Even the pyramids won't last forever and if you want your society to be sustainable you need to factor in maintenance. And often times maintenance is a harder problem than the initial creation.

Maintenance also informs builders on what can be improved next time. For example, we now know that rebar reinforced concrete will eventually need to be replaced due to spalling. If we reinforced with glass or basalt rebar that problem is solved. It might fail a different way but it won't be from spalling.

Over time we learn to build structures that last a long time and require less maintenance. Unfortunately, building codes are often very specific. Sometimes requiring specific materials. Using a different material requires proving it is a suitable replacement before construction. We have to allow builders to take risks. Sometimes we get a Tacoma Narrows bridge, sometimes we get a Hoover dam. But, the builders have to be able to try new things even if we get a few stinkers once and awhile.

Excellent points: I learn more from maintaining code than from writing new code.

Tell that to the New Jersey transit trains that get delayed 15 minutes every time they go in and out of New York.

That's just as nonsensical as the classic "Everything that could be invented has been invented already."

You didn't read the article. It talks a lot about housing, high speed rail. Those are just two things we could be building right now.