Most RPGs tie the player to a very explicit code of morality, defining their personal character within varying shades of good or evil. In these situations, saving someone would be considered a good act, while killing someone else is frequently seen as a vile deed. These extreme points of view frequently don't take into account that there could be more to these actions than it would initially seem. For example, players might discover that saving a person allows them to commit heinous crimes that you'll have to deal with later, or that killing a supposedly innocent person prevents the deaths of dozens or hundreds of others. On top of this, aside from agreeing or grousing about a decision, the impact on your party is relatively minimal. As a result of these limitations, you play more to a pre-defined sense of good and evil than making your own path, determining what works for you.