Well, homunculi can be tailored to be magi, or assassins, or just about anything. They're useful because they can be "programmed" with any set of skills. In this setting, for example, there is a homunculus to whom killing is as natural as breathing.

As for the situation, it depends. A homunculus could be created to aid an organization, fight for them, to be the ultimate assassin, any number of different things. A homunculus needs a human soul to be created and therefore creating one involves the death of human being, or something with a human soul.