Airlines and pre-boarding are another thing that is backwards from what should be done. Anyone that is infirm should be boarded last in case the plane needs to be cleared for some reason, they are then not stuck on the plane and in harms way. Airlines like SWA that don't give reserved seats in general should in these cases so the person can board and not have to worry about seats. No airline in the world allows people with young kids, the elderly, and the infirm to pre-deplane. In fact they announce for them to stay in their seats and the staff will help them after the regular crowd shuffles out.
As far as kids pre-boarding, if they can walk they should join the herd. Infants can be carried so they can join the herd too. I have four children and when they were young we didn't pre-board as I didn't feel we "needed a little extra time".
I'm premier and elite status on three airlines. If I'm not upgraded to business, then I will pre-board under that call as I've earned the right through many seat miles at premium prices. That is a lot different than the general pre-board critieria.
Flame away, this is my two cents and I'm spending it.