Babies on planes stress me out when they are wailing, so I can see someone paying full F/J being annoyed about not being able to enjoy their experience as a result. However, in maybe 100 flights last year in J, I'd say I was bothered by a baby maybe twice.

I can only see this being fair on a 3-cabin airline. F/J/Y - I think on AC it would lose them too much business from people taking their J-baby business elsewhere.

I think this is especially relevant on over-night transatlantic flights. What if they had a baby-free flight? For example, only allow babies on the daytime/6:30pm LHR flights, but not on the 8:30pm or 11:30pm flights. I think that could be a fair compromise... but I don't see this happening anytime since AC is not really hitting the same kind of F customer that they have in Asia.