Now, why people rush for their seats when they have assigned seating (assuming the baggage storage space isn't a big consideration) is another human psychology conundrum, but anyway... People do rush: they stand in line for the longest time, and when their seating area is announced ("Section 1 may board now") they rush towards the gate, knocking children and old people on the way, knowing well they may have to wait again for quite a while, as people in front of them take their seats.
Now, airlines make a big deal of optimizing their gate turnaround time. So why on earth would they have people board in an order that is bound to generate queues and be slower? People take time to stow their baggage, get into their seats etc. and hold up people behind them who're typically trying to get to seats behind.
Isn't the logical thing to do, to ask people who're going to be sitting at the back of the plane to board first? Assuming that people continue this not-completely-understood-by-me behavior of rushing on to the plane, you should have less incidents of people being held up, and theoretically complete boarding faster. What am I missing here?
The only thing I could think of was that it might be some kind of prestige issue: you want first-class to board first, and the rest follows. Since now United is price-discriminating, they may want the people who've paid more for the economy seats in front to get on first. About the price-discrimination tactic btw: as always, the student of business in me strongly approves, the human in me is indignant.:)