What is significance of 'comic relief' in shakespearean tragedy?

If a play is too serious and you just have tragedy upon tragedy then the audience will being to laugh at the tragedy. Not a result that playwrights aim for. So to keep them from laughing at the tragedy they slip little bits of comedy into the play so the audience can have their laugh, relieve the nervous tension, and get back to the grim stuff. Shakespeare understood this and inserted clowns into his more serious plays to provide the comic relief. When Cleopatra order as asp to commit suicide with the clown that brings it to her and remunerate all the virtues of such a death, how nobody ever came back and complained, and such clever things.