A natural consequence of the inherent nature of all tabletop gaming, I think, is the quantification of people, with all the ethically troubling rearranging of priorities that that act implies. I think that helps to explain at least a part of why the stereotypical D&D adventurer (even a supposedly "good" one) tends to be morally freewheeling and casually homicidal - quantification facilitiates objectification.

(Of course, it also helps that the excitement in most tabletop gaming is centered around over-the-top fantasy violence, and as such, both the players and their characters must start with the assumption that over-the-top fantasy violence is fun, interesting, and morally justifiable. Also, it helps to live in a world where "good" and "evil" are obviously measurable forces, like magnetism. And, I suppose, the existence of magic that instantly heals the normally gruesome consequences of violence also contributes.)

Gaming as we know it would be nigh impossible if the answer to "How important is this person?" was always "Infinitely so.", as many ethical systems would demand.