I believe that it's more about protecting the image of the artwork. Imagine using the statue to promote product X. Then imagine that every icon/building/etc. being used to promote something that you/the nation goes against (i.e. the statue in the cover of a porn magazine, or a historical monument to promote the latest crypto-fraud-coin. I understand that the Colosseum, the Acropolis, or the statue of David won't be physically damaged by such an ad, but still..