Anyone arguing that they should be given any special privileges because they decided to reproduce is WRONG. Preboarding and the group system in place currently are based on legitimate need and loyalty for achieving criteria that UA has set.
Children are not a disability (unless the child is disabled and then they should preboard). It is a choice (in most cases) to have a child and inconveniencing others as a result is not fair.
I can't tell you the number of times that I've had to listen to a child screaming, see them running around, making a mess or just wreaking havoc in the airport, UA Club, or on the plane. In most of these cases the parents just sit back and let the child blast a TV show from his/her iPad while throwing Cheerios everywhere.
UA should not further reduce benefits for its most loyal elites and for those buying and/or seated in F. Here is a perfect example from a travel blogger asking if the policy can be amended to age 3, 4, or 5:
http://michaelwtravels.boardingarea....flying-united/
I guarantee that we'll see tons of examples of preboarding being abused after February 15th. As it is now, I see plenty of GAs allowing people from other groups to board with Group 1 because they play dumb or act confused and board out of turn.