What is art is a harder question tbf.
Its also contextual (for me) as someone copying Jackson Pollock is not the same as Pollock or Basquiat for instance, since he created a new way to do art - taking from others pollock being one
Discussion
Just as a side question .. are we asking if art should have meaning for the observers/appreciators, or that art should have meaning for the artists/creators?
We'll say creators
In that case, I believe that the question of whether or not art should have meaning is moot. I feel that once the piece is created, it has fulfilled its purpose as an expression of meaningfulness for the creators .. like a form of "living in the moment". Again though, it's very subjective, and I am just a pleb with my own appreciation for the human condition that is "the journey".
A friend of mine likes to create a piece, he looks at it for a few weeks, then he has to give it away .. for him, the piece represents a part of himself that he doesn't want to recognise, or has moved beyond, and so the meaning he gave to it is now lost to him.