Meh…I travel fairly frequently due to work and I've never found children on flights to be that much of an issue. I've certainly been on a few flights with crying children and of course it can be slightly annoying, but I think people exaggerate this issue and make it out to be a bigger problem than it is. Just put some earplugs in or, if possible, ask if you can move seats.
I don't have kids and I'm not sure if I particularly want them, but every parent I've seen on a flight doesn't look like they're having that much fun. Kids have to go on vacation too, and to visit relatives in other countries/states and travelling with them looks like a fucking nightmare. I can't say I'd enthusiastically get behind a initiative that sought to make it even harder for parents to travel.
The other issue is that once you start excluding certain people from flights, it's a slippery slope. What about fat people? Or people who stink? Or people who travel together and talk the whole way? Or people who get up to use the bathroom every 20 minutes? Flights, by their very definition, are full of annoying people who are all up in your personal space. If you can't ride that out for a few hours, you should probably work on your own tolerance levels.
EDIT: Reading this thread reminds me of that Louis C.K. routine (yeah yeah, masturbation, I get it) where he talks about how shitty humans are as a species that we will find something to complain about even in the most amazing of circumstances. Case in point: you are taking part in the miracle of flight, being whisked through the clouds from New York to LA in less than five hours, and all we can do is get annoyed that there are other people on the flight with us. That journey used to take 3 weeks on horseback, and a bunch of us would die along the way. We all need to seriously get over ourselves and appreciate how lucky we are.