As for "Why not remove so many of the minimums...(...I don't need prenatal coverage)" The answer is: The exchanges are an attempt to bring the benefits of group rating as enjoyed by employer sponsored insurance to the individual market. Those benefits include preexisting condition coverage and overall lower premiums. The cost of those benefits is that everyone in the group gets the same coverage. So, while you, personally, may not need prenatal coverage, people in your group that are helping to keep your insurance rates more stable and (hopefully) lower than they otherwise would be will need that coverage. Likewise, coverage of contraception keeps rates lower because pregnancy is expensive.
Now, are there going to be people for whom the new system is worse than the old one? Sure. And if you're one of them it kind of sucks. But the expectation is that the people who are harmed will have enough options to be able to deal with that harm while those who are being helped did not have any options without the implementation of this law.