My father served as a Minister of Music when I was growing up, so I've got quite a lot of experience with Sacred Harp Hymns, new hymns, and contemporary music. I think they all have their place. Those songs you call old hymns, some were originally drinking songs. Fanny Crosby (Blessed Assurance, I Am Thine oh Lord, etc) often used secular tunes. The Salvation Army did it as well. The whole point is remaining relevant in the evolving culture. Good churches are constantly trying new ways to reach the lost. I'm not saying it's all effective or completely pure in motive, but the best part is that God can use anything, regardless of how much we humans mess it up. Contemporary and traditional services both have their place because they allow people to worship in the way that best speaks to them.
Some of the additional buildings that churches build seem unconventional but are designed to meet people where they are. For instance, the church we attend built a new sports complex a few years ago. It was built to serve a community need for more safe places for children to get involved in sports because all the church leagues in the area had waiting lists. The complex is free and open to the public, and while there is a small coffee bar in the main house, we added it so moms could sit and talk while watching their kids play. Church members of all ages are encouraged to go to the complex and build friendships with people who use the facilities. So it's truly an outreach ministry. All that to say that some of those buildings really do have a higher purpose and while they may not be for you, they can reach others.