At first you made me think that you AGREED with disrespecting heroes. If you want to ANSWER those who call heroism banal, that's very different. You need to make sure that people understand what it is you're saying to them.
For starters, have you ever heard of the Peloponnesian War? It happened in the neighborhood of 400 B.C., when the city-states of Athens and Sparta fought over who would be the dominant force in Greece. The reason why I mention it is because of an illustration it gives--an illustration involving the Athenian statesman Pericles.
At the time of a group funeral for Athenian warriors, Pericles was asked to give a eulogy for his fallen friends. In the speech, he remarked that persons who hear about the deeds of others often refuse to believe what they hear, if the deeds being described are greater and better than what the hearers would be able to do.
Do you see why this is relevant? In the modern world, there are many authors, teachers and so on, who have NEVER had to risk THEIR lives for any noble cause. Because of this, their selfish, prideful ego does not WANT to believe that others might be true heroes.