Your body makes contact with the saddle at three points: Points one and two, your sit bones, are also known as the ischial tuberosities. The third point is the soft-tissue between your legs. Whereas sit bones are designed to withstand body weight and pressure, the soft-tissue of your genitalia is not. During long rides, the pressure exerted on soft-tissue can cause painful skin irritation and constrict blood flow. This can deaden the nerves.
Though a 45 minute or one hour ride may not be considered long, for women spinning multiple times/week or doing back-to-back classes (increasingly a phenomenon) there are clear benefits to wearing padded gear and clear risks to not doing so.