One of the great ironies of this issue is that insurance companies actually have a HUGE incentive to cover contraception. It's cheaper for the to pay for contraception than for the costs of maternity care, childbirth, and pediatric care.
Better yet ... this is a huge incentive for EMPLOYERS to insist that their insurers cover the cost of contraceptives.
The mandate, therefore, helps the insurance companies. But if there were no such mandate, people could buy policies that dont include contraception for less money. Companies that offer such policies, perhaps smaller companies, would find a market for their products.