There are many reasons to build a new church. Sometimes the old one may have been destroyed by a weather event. The congregation may have outgrown their present church and need more space. A group within the church may want their own place of worship nearer to their homes. These are all valid reasons to build new churches. The problem is often one of money. Churches are not businesses that rely on profit. They are houses of worship and rely on donations for income.
While churches often had their own lands and income in the past, this has not been the case for centuries. Many churches have just enough land to hold their building, parking lot and an activity area. Donations are critical for maintaining the building and providing services for the congregation. Building a new church is a massive undertaking for many congregations. Most do not even have insurance in case of a weather event.
The world economy has not been overflowing during the past few decades. Churches have found it takes a great deal of time to collect enough donations to build a church. Even if the congregation already owns the land, this is a struggle. The builder must find ways to make building as low cost as possible. The church must be easy to maintain and fit the congregation, but extras are often not part of the original plans.
One of the extras people may miss in their church is stained glass windows. These are very expensive to design and build. Modern churches now use clear windows and apply decals for glass or glass transfers. They get the same effect as a stained glass window at a fraction of the cost. This is one of the ways modern technology can keep costs down when building a church.