This drama set at a California racetrack boasted the rich density of David Milch's writing and a king's ransom of a cast: Dustin Hoffman, Nick Nolte, Dennis Farina, Jill Hennessy and Richard Kind for starters. It explored a strange and fascinating world while capturing the horse races with breathtaking footage. But three horses died during production of the series. That sad fact, and another -- the show wasn't exactly a ratings blockbuster -- led to HBO canceling "Luck" after its first season, in a bow to bad publicity led by animal-rights activists. Amid the hubbub about the horses' welfare, there was a question no one seemed inclined to ask: Assuming every reasonable precaution had been taken, was risking the lives of a few horses an excessive price to pay to keep an excellent drama series on the air?