Wow, thanks for reminding me about dog fighting, I totally forgot about that...but that too is indeed another "dog sport". And yes, the Iditarod isn't as bad as dog fighting, I agree.
Animal Planet had betta fish (Siamese Fighting Fish) featured on an episode of one of their "top 10 something" (I don't remember what it was called exactly, but the graphics were always that neon green color), and they mentioned that the fish used to be used in the same way that pitbull dogs are used today, for fighting till the death.
I think there must be something really awry with someone who takes pleasure in watching a totally un-natural, staged fight to the death between two domesticated animals that never would've fought like that in the first place. *Except for the betta fish, two males will fight, but I'm sure in the wild it occurs less often than with human intervention. Plus, in the wild, it's natural, and ok to watch, and actually bad to try to stop it.
Anyway, I totally agree with you. Its completely understandable to me why people enjoy watching it [the Iditarod], b/c it isn't outwardly brutal like if they televised dog-fights. Parents wouldn't want their kid to watch a dog fight, but they wouldn't mind letting their kid watch the Iditarod. Its just that some people read into it more than others.