I actually thought the movie did an excellent job of showing that attacking the hijackers was not a simple, UN-thought-out event. Specific planning went into the attack: what weapons do we have, gather up those weapons, move all the big guys up front, go fast, assign/take on specific tasks ("I'm going to break his arm"), what do we do with the plane after we take over, who will fly the plane, can he fly the plane, make calls home to loved ones, time the attack, etc.
I thought that part of the film was particularly good because it showed there's more to taking back a plane than just disabling the bad guys in the passenger cabin.
Isn't it amazing what people are capable of when they've had more than enough and won't take any more? The part that breaks my heart is that the passengers were so close at succeeding, as unprepared as they were, in overcoming what a purpose-built set of systems were unable to stop. Ladies and gentlemen, as the Great One says, "You ARE capable of great things! More capable than you know!"