Pffft. Sure a machine can decorate perfectly proportioned pieces of cake. However, in a tube cake pan crisis, you need a human. Rescuing lumps from a greased and floured pan, and then molding them back into a nicely decorated, cake-shaped treat with nothing but icing, toothpicks, and sheer determination* - that requires an artist! 
*or desperation, due to a lack of enough time and/or ingredients to start over again
