I now carry a Bose noise cancelling headset, so noise is less of a concern unless they are really loud and right next to me. Then it would be frustrating.

But I think airlines can get around the question of wether infants should ride in First by levying a charge of somesort for infants riding in First.

As for changing diapers; IMO if the lav is equipped with a change table, they should use it.