I had the same experience on a LH flight from CLT to MUC - the longest mentally challenging flight of my life. Everyone has a different level of sensory aversion/defensiveness and I am a mom, so I get that you can't always console your child. They might have inner ear problems or some other discomfort that they can't articulate because they are...well...babies. I think it's impractical to ban children from flights as this seems a bit draconian. But, I empathize with your frustration. Listening to a screaming child for hours and hours is like torture and can definitely push the limits of your emotional intelligence. I also agree that the noise cancelling devices don't seem to be made for baby decibels. It would be awesome if they had a lavoratory type space that was sound proof so you can usher the baby in there until they stopped.
I'd like to stick the snorers in there as well!