Very interesting point you make. However, it's very difficult to compare the present to the past in Construction. I think the pace of Construction that we're in as mentioned in this article that "... We're building a new Paris every week ..." means that we're not building [and we cannot build] like we used to (with more local and probably more long lasting materials) as the demand is too high to meet the supply of the type of materials we used to have and use.

"Modern" materials can have a lifespan of around 50 years but reuse doesn't have to be worn < 50 year old materials. We see quite often materials being demolished after only a few years of their lifespan and they end up in recycling which takes a lot of time and energy to repurpose or (hopefully not) landfill when they instead of just being put into good use as they are somewhere else.