I dont' think this question really can be answered very easily. I don't necessarily adhere to the ideas of "primal instincts" or other ideas that it's related to animalistic nature but I do believe it has to do with men (generally) being wired differently. You could possibly pose the same type of question to women that had breast cancer end ended up having surgery to remove their breasts. It affects them very strongly too, I believe. I think it's very similar to how men feel about their "manhood" and their ability to use it.