Putting an image on the end of a stick and waving it around adds emphasis that you don't get when the same image is lying flat on paper.
For example, soldiers aren't likely to follow a nice lithograph into battle no matter how tastefully it is framed. They would not die fighting to keep their enemies from taking down their country's oil painting. And while composers have written stirring songs to the "star spangled banner," no one seems to have been similarly moved by a star spangled silk screen print.
I don't know if this is due to the fact that moving images attract more attention than static ones, or that graphic symbols typically serve different functions when they are placed on a flag, or just the excitement of marrying a picture with the wind. But somehow images are a totally different artistic experience when they are placed on a banner in a parade, or a flag leading a charge, or a tapestry wafting in the breeze.
Here are some designs on flags and banners that I think are really splendid:
It would be hard to appreciate-- or even see-- the subtleties of these lovely designs once these banners are in use. You just have to remember what they looked like. In that sense, loose cloth is an odd medium for visual art. But I suppose the wind contributes its own designs; it may sacrifice detail but it gains a lot of drama.