Seems to me that killing the innocent doesn't make a good hunt. From Hircine's quest, he's pleased if you kill the were wolf or the hunters that follow him. I imagine it's along the lines of "The Most Dangerous Game" -- hunting a man who can also hunt you back.
Hence, "and the mortals."
Hircine is pleased when the innocent are dead. He also seems to like the "pure" to be hunted. In Oblivion, you were tasked to kill a White Unicorn, in Skyrim, a Great White Stag. But on a more proof-worthy note, in Daggerfall you had to kill an innocent person to be fully sated and appeased. In Bloodmoon, to cure Lycanthropy Hircine demanded a sacrifice for the ritual; flesh and innocence.