For the life of the flesh is in the blood: and I have given it to you upon the altar to make an atonement for your souls: for it is the blood that maketh an atonement for the soul. Leviticus 17:11 (King James Bible)
Life. Family. Death. Passion.
Blood symbolism is important in many works of art and in many cultures. In contemporary Western culture, it is one of those things that we try to keep out of our sterile public space. Kathleen Norris has, I believe, rightly picked up on this discomfort in her Amazing Grace: A Vocabulary of Faith. But repression brings about inevitable backlash that will find some means of expression: as blood has disappeared from our hymnals, has it splashed in ever greater quantities on the screen? And what monster has been more prevalent in entertainment than the vampire in the past couple of decades? It is in the archetypal vampire novel that we see the verse above from Leviticus quoted prominently. Of course, some of these entertainments have attempted to take the monster out of the vampire, but even these trade on keeping something of the eerie, Gothic atmosphere. When and if we became inured to the power of blood, these stories would lose much of their power.
Religion and magic, two important elements in mythopoesis, have powerful symbols like blood as their stock-and-trade. It can be powerful whether used subtly or profusely, just so long as it is used in such a way to draw on its power, give a feel to the setting, and capture themes in that hold the plot together and move it forward.
For one example of how blood has been used in a less-than-serious world, see this old post. Note, however, it would work in a serious narrative world.