If art piece X is available for people to see and think about, why is artist Y not allowed to use it to create even better art? Why is company Z not allowed to figure out even better ways to monetise it?
You probably think the money lost by A is greater than the money gained by Y and Z. I think that's not true - a lot of great art is derivative, and a lot of interesting business models around art have not been explored because the incumbents (A) resist it.
You could also argue that A won't be incentivised to produce the art, but... actually, if only one country does this, that's not true.
PS: China doesn't count, yet, for two reasons: 1) it's not a western democracy with a long tradition of western-style art and copyright and a hunger to innovate on the art distribution models; 2) copyright theft is not actually legal there, it's still illegal, just loosely enforced; that prevents real legit businesses from emerging in that space.