Macromutational monsters

Homeotic mutations are examples of macromutations, that are sometimes called 'Goldschmidtian monsters' after Richard Goldschmidt who suggested they might be important in evolution. They are mutations of large phenotypic effect. Their mere existence demonstrates that macromutations can arise. We can imagine that even more monstrous phenotypes might be generated by mutations in genes controlling early development, though mutations with too radical effects would be lethal and never emerge from the egg stage.

But how important are these developmental macromutations in evolution?