Why the Tradition?

I've been looking at posters, advertising, signs, packaging and design in general and am interested in the fact that particular messages are communicated using specific medium. What I mean is exemplified in the poster below. This blue, hand painted type is often associated with church posters. It's quite crude but in a strange sort of way I think they're really cool! I don't think they're meant to be cool but that's probably because of what they're communicating. Maybe if they were for something different, that would enhance them and show them off.