It's actually an interesting problem from a "total effort" viewpoint.

There's zero reason to design a kitchen to last 100 years if the average one will be remodeled in 7 and even the oldest won't go past 20.

But other things can be designed to last significantly longer, and be used way past their "original expected lifespan" - many of the buildings in Europe, for example, have lasted centuries.

True.

That said, w.r.t old buildings, selection bias may play a significant role, perhaps bigger than intentions

And maintenance costs, too. You may have a bridge that's 100 years old but you're paying 1/10 a new bridge in maintenance every year - not noticeable.

There are also other factors. Imagine you gave a 500yo bridge that is low maintenance and has stood the test of time and all those nice things, but you can't carry the weight of modern vehicles, or if it's not wide enough for modern vehicles etc etc

One of the many tradeoffs in design is how much do you want to spend in preparing for anticipated future demands.

Striking example in my home town of Zagreb. Communist city planners at the time designed new neighbourhood with plenty of parking space because one day productivity advancements will give every family a car to own and they need to have a place to park it!

A few decades later you couldnt find a parking space anywhere because every family had two or three cars!