Paul Riser might get life in prison, for example, because he was good in Aliens. Murphy Brown would have no defense. Everybody hates you. Because you're phone companies. At least there's some justification for phone company commercials.
Phone companies have to compete with one another, somewhat.
This isn't the case with utility companies. But that's not really why they do it. The real reason these monopolies have started advertising is because it makes the executives in charge feel like they're running businesses even though, really, they're not. A business is something that competes against other businesses. The water company isn't a business.