Making pedos happy is good for society, too. We just want a world where more people are able to be happy, and where people's lives aren't ruined just because they wanted more joy in the world. Since when are you only allowed to campaign for positive change if it doesn't directly affect you?
Also... The people making the rules are mostly not thinking that they're the ones who are going to get with all these attractive children once they hit a certain age. If anything, we'd be "taking" these girls off the market from their age peers, who are children themselves, and not really in the position (yet) to shape the fabric of society.
So, why exactly are we losing out to a bunch of immature adolescent boys? God knows the girls themselves love us.