Not to revive the "when to start your own evac" debate, but I just wanted to point out it's worth considering the effect of Asiana being fresh in pax's memory. Most everyone in the general public has seen footage of the burned out fuselage, and I bet many on this SWA flight were thinking "I'm getting outta here before that part." Granted Asiana took a while to look like that, and there's no comparing that fire to this incident, but it doesn't have to be rational -- a vivid mental image has a lot of power.
Just to illustrate that, in post #124's video you can hear people shouting "we need to open the doors" almost the instant the aircraft stops moving. Both there and in post #149 you hear the CC immediately telling people to stay seated, but then you hear "no no no" and "we gotta get out" -- and in the second video people start shouting about smoke (maybe only visible out the windows, who knows)... easy to see how a herd mentality takes over at that point.
Anyway, I wonder if the reaction would have been different had this been before Asiana (or many month/years afterward).