I agree with ed; it's dangerous primarily because of the way many cultures value men over women. When you get to a certain point and the females have been eliminated from a population, there arise serious social concerns as well as problems perpetuating a population.
Not that the latter would be BAD for the world right now, but we're probably not responsible enough to administrate it properly.
Now, the reason other people make a fuss over it? Because people are, for the most part, sheep, and religious zealots like to stir up controversy over anything that gives people any reproductive choice. Besides which, the media likes to play up any minor controversy and turn it into a huge thing that it's not, in reality (see the American media with the so-called "Mommy Wars" during the past twenty-five years).
