What expresses the most in art, IMHO, is the nuance and not the broad strokes. In music, for example, many people can play the notes in the right order; it's the great musician's nuance that makes it art. In acting, it's the tone and subtleties in the actor's voice and expression. Reproductions don't capture that; nothing matches seeing it in person. I've tried high quality reproductions of 2-dimentional works I love, and it's not even worth it.

Also, much artwork these days is 3 or 4 dimensional (time), so 2-D reproductions have even less fidelity.