I love them, when they are well done.
They don't have to be made the day off, I've done 2, just wrap saran wrap tightly around the exposed cake, and leave it on until the last possible minute, then spritz with a soaking syrup.
They are actually way harder than they look though, the people charging way less for them are the people producing the sloppy messes with icing gooping out of the sides.
They have to be perfectly torted, sides smoothly carved, filled just so, and obviously extra care has to be taken so that nothing goes stale.
I charge by ingredients/supplies + misc overhead + time, so they save some money on ingredients, but labour wise it costs just as much as having a flat iced cake.