1.) Heroes like Iron Man and Captain America fight villains that are interested in destruction, crime and the subsequent harm toward innocent people. There is nothing wrong with admiring the heroics of these guys, especially when they are inspiring the imaginations of children everywhere.
2.) Heroic, self-aware robots called Autobots come to the planet earth to save it from evil robots who would otherwise enslave humanity and steal the planet's sources of energy. What's wrong with cheering for the Autobots who voluntarily risk everything to save humanity?
3.) Cowboys, outlaws, sheriffs and train robbers may be things of the past, but they inspire today's writers in many ways. Han Solo, a central character and hero from the Star Wars saga, is based loosely on the rebellious, yet heroic outlaw type of personality. Same thing can be said of the primary characters in Indiana Jones, Big Trouble In Little China, Rambo, Die Hard, etc...
The writer needs to chill out, and let today's heroes continue to inspire and provide something to cheer for.
This tells me that in very large numbers, people do not see anyone on the leadership scene at any level who inspires confidence.
I'll go one further. As a big X-Men, FF, and Avengers fan---even JLA if they got rid of Batman and Superman---what made those teams so appealing and all-American was that each person had distinct talents that were entirely individualistic, but not super-powerful. To defeat the bad guys took team work, but not communist-style teamwork, American individualistic team work. You NEVER forgot the Human Torch's individuality, or the Angel's appealing arrogance, or Iron Man's secret weakness. Usually, the movies captured this in their first iteration.
Comics lost me when the villains got to be so titanic, so (literally) galactic that really no combination of human effort could stop them and it was only intervention from god(s) like the Silver Surfer that people gained victory.
BTW, "Cowboys vs. Aliens" looks terrific, with or without 3-D.