I'd like to see some links for your assertions that a woman is less likely to get pregnant because she's not aroused.
Also, just how rare is it for a woman who is raped to get pregnant? I've read that 5 percent of women who are raped in the USA get pregnant. That's 32,000 women every year. But even if its 1 percent, that's between 6 and 7 thousand women per year. I wouldn't dismiss that figure.