It's simpler than many are making it - many prescriptions are already cheap/free through insurance; this is just one more. The only reason it is such a big issue is that it is "morally" charged. The main political point is that it is unfair to keep any prescription expensive (relatively), when if it were any other drug, it would probably be covered. It isn't right to avoid covering it just because some people don't like it for biblical reasons. (and that cheap/free contraception saves a ton of money/grief in the long run)

Edit: I should also mention that Obama is focused on making preventative care as cheap and easy to get as possible, on the basis that it is much cheaper to prevent than to treat a condition. In addition to all the money that can be saved by appropriate family planning, contraceptive medicine is being treated as a preventative because of the numerous other issues it is prescribed to treat (different types of cancers, PCOS, endometriosis, etc).