Why would they build? They're losing members year over year in droves. My parents are at that unfortunate age where a lot of friends and family are starting to die, and one constant refrain in the area is "when can the funeral service be? will a priest even be available at the church that day?" My grandmother died recently and they had to wait for a day for a priest to be available at that particular church because he holds Mass at three different physical locations in the area due to a lack of faithful. And this is Southeastern Louisiana, which is about as Catholic as it gets.

Anecdotally, I see a lot of of dwindling in membership (and, it at least one, even schism) in established protestant congregations (Methodist, Presbyterian, Lutheran, Anglican) - many of those buildings having literally shut down - and converts coming to my local Catholic parish, as well as returning practitioners of the faith.

It's hard to imagine the Catholic church being as prominent in the world as it once was, of course, but as member myself, the last couple of years give me hope that we might again start growing.

While the decline is not universal, shrinking parishes is itself a reason to sell older and more ornate churches and either build smaller strip mall ones, or merging several parishes into big expo center ones.

Of course it only adds to the decline when the hierarchy builds as if going to Mass is no different from a trip to the mall or seeing a show.

There’s also the hypothesis that if the Church gets prestigious awards for their avant-garde architecture people will finally start liking the Church again.