We aren't building a lot of stuff these days, so maybe it's just that we've lost the scale needed to support the skills to do construction well. Back then populations were growing rapidly; there was also rebuilding after WW2. GDP growth in France during that time was maybe 5%/year. Today? Almost flat.

Today, that massive construction is occurring in China, at least for the moment. But even China is installing renewables and storage at a much larger rate than they are building nuclear plants.