I sometimes find it a shame...

[Sheldon]

Anything that society is in practical want or need of, obviously. You're a theist, surely imagination is not something you lack?

The church was generally the one who provided that as well; the cathedrals you are referring to were largely built by local guilds and communities coming together and wanting to build a shrine to the uniting thread that binded them, to glorify God's kingdom on Earth.

1) What churches provided varies wildly, so this is a rather facile generalisation. 
2) I referred to no cathedrals specifically of course, but how they were funded rather misses my point. 
3) I made no comment on what motivated people to build such edifices, so this doesn't really address my point either. 

There are plenty of scientific reasons as to why this is good for a society as well, 

I am dubious, especially since all you have offered is a bare unevidenced claim, but this again, has little to do with my point. 

so I'm just not sure what would have been necessarily more practical.

Than vastly costly shrines to an an imaginary deity or deities? Maybe I was wrong, and your imagination does not extend beyond imagining a deity. I can imagine endless possibilities of the application of such resources that would have been of a more practical help in providing for basic want and necessity.