The State you migrated from must have mandated it because here in Colorado during that same time period if you wanted contraception prescriptions covered by insurance you had to purchase an individual rider on your policy to have them covered. Making one's self infertile is an elective choice and as such should be paid for by the person making that choice for themselves. I agree that when used as a hormonal treatment to correct an imbalance they should be covered and to differentiate between the two is a simple coding exercise. If a doctor is willing to risk their license to defraud the insurance company under such a system then fraud will occur, but at least there would be a remedy for the fraud.
And no, pregnancy is not a medical condition that requires medication to prevent, it is a binary physical state. There are millions of women who are both healthy and pregnant which is all the proof necessary to put such nonsense to rest.