Why  can Children  only perform music when they are on an adult level?

Public displays of Children's artwork can be stunning, the painter's emotions are communicated for all to see and feel in a breathtaking and clear fashion.

You don't see people criticizing them, making fun of their perspective or the type of brush, canvas or paint they use.
Why it is so when children produce art in music form?
Are we that impatient and foolish that we can't listen to something that may not be what we perceive as perfect in its execution, however has moments of genius?

Can we allow children to express their art without fear of withering criticism?
Lets allow them to grow in confidence so one day they will be able to withstand the inevitable jealous vitriol (and be able to label it as that and not be injured by it).