It's not plagiarism, but this gets to the reason that I don't enjoy photographing art or architecture. With this kind of photo work I am guaranteed to be piggy-backing on the artistic vision of someone else. For this reason, I prefer the "found-art" feeling of landscape work or the challenge of capturing the uniqueness and individuality of a person's portrait. If an artistic installation is done right, a photographer can't lose--amateur or pro. That isn't challenging or rewarding work to me.
In this logic a painter depicting some architecture masterpiece is also piggy-backing. Art is and always was a blending of ideas and interpretation of things.