Probably the same folks that continue to tell us not to resist armed robbers - "your money isn't worth your life". Well, given an opening, I'll resist all right. People forget that humans are capable of being quite barbaric, even if only for the contents of ones' wallet. Plenty of times, the robber not only takes the money but kills the victim as well.
Sadly, this is true. It is only the folks on the last plane, after hearing the fate of the 3 hijackings before them, that decided to act and save many more lives.