Please, it’s not about guaranteeing blood. It’s giving Muslim men their fill of female pain for the day.
Although many times the pain of a woman’s first intercourse is actually not caused by the hymen but by muscle clenching/spasm, I am betting that a surgically restored hymen is less stretched, flexible and worn down than that of a typical 20-something woman (who even if she is a virgin, would likely have engaged in many athletic activities that stretched if not torn the hymen making it a non-issue for first intercourse - which is one of the major reasons why many women do not bleed). Thus the woman will be in pain, thus the Muslim male is happy.
Good point.