It's been said on twitter that the reason they are so annoying and seem to be dicking around rather than actually landing is because they must be billionaire aliens in their spacecraft. Now that is more plausible.
Douglas Adams wrote something similar long before Twitter existed. It's in the Hitchhikers series. Brilliantly phrased, as you'd expect, but the gist of it was that they were adolescent aliens messing with people from primitive (to them) civilisations for their own amusement.