As someone with no small children but who also appreciated early boarding when I travelled with my mother who used a wheelchair to go long distances and needed time to get in her seat, with me carrying my carry-ons and hers and maneuvering a wheelchair down the ramp, I don't think its not unreasonable to give a couple or a single parent or couple traveling with a small child time to board before the rest of the passengers.

I just hope that there are specific limitations that will be announced about who can board with the small child (I guess it has to be parents and all minors) and how small the child has to be (24 months? stroller child??).

I have seen myself abuse of early boarding privileges often (eg. where on an EWR-HNL flight, a purportedly disabled (but seemingly ablebodied late 50s grandmother got to have her 12 relatives board with her, including teenagers and adults headed to a family reunion). Also I have on other airlines pre-boarding by parents with a 10 year old kid that was clearly not the "small children" that the courtesy was intended for.

But if the rule is correctly enforced to only help those who genuinely need extra time, this is not going to delay anyone's boarding by more than a couple minutes, if at all, and would be much better for those struggling to cope with a baby in arms, carryons diaper bags, and possibly other small children, so I guess we shall see how this plays out. As with many rules, how it is applied is often the determinant of whether it achieves its purpose.