Well, calligraphy is an art form in both Chinese and Arabic.  But that is also true of other languages, e.g. English and Hebrew.  It's just kind of curious that the phrase wasn't rendered into any other languages, and that there's no indication anywhere for non-readers of Arabic or Chinese as to what the banners actually say.  So in order to "get it," you'd have to be able to read one of those languages.  Which, as you point out, not a lot of people necessarily can.

(NB:  Colloquial spoken Arabic and written Arabic are very different, and I know quite a few people who are the children of immigrants and have grown up speaking comfortably in Arabic but are completely unable to read it -- not even street signs, let alone calligraphy, which at its most ornate can be difficult for even fully literate native speakers to decipher....)

At any rate, they are lovely banners.