Except that the point of an interactive game is to shape history, not relive it, which could be done better by watching the History channel or reading a book. So pigs and dogs were used, in a small scale. But now you're the leader, not some ancient dude who thought animals were not worth it. Maybe you want to create an entire army of dogs and pigs and found that the hilarity is worth the coin. That's your choice.

Isn't that the point of playing this game?