Two reasons I don't at all support an infant ban on AC.
1) Maybe I'm lucky, but I recently took my 3-month old on her first flight.
Result: absolutely nothing. She started to fall asleep during takeoff and didn't make a peep for the full three hours. I hope that's not a one-off thing, but not all babies are going to cry non-stop. Banning babies based on a subset is no different than banning anyone who's had anything to drink from flying. And how many people would pay more to fly a dry airline to avoid loud drunks?

2) I've only been in AC J once with an infant (that I'm aware of, so maybe they're better behaved than normal) but it still sticks in my mind how the crew went far above their job descriptions and looked after that kid for the entire flight to LHR. I saw at least four different FAs wandering the cabin holding him so his mother could get some sleep/food/rest. And the result was a very well-behaved infant and a happy parent (and some FAs who seemed to be really enjoying the flight, too). If they offered this service instead of a ban, I think we'd find a lot more happy pax and probably more revenue from parents who would spend the extra for it.

Maybe the next time I'm on a plane I'll be eating my words about infants (particularly mine), but my personal solitude on an airplane is not so important that I should be demanding everyone else control things that are fundamentally uncontrollable (well, we can do things to help them stop crying but it's not preventable) to fit me.