Another tip for big banks trying to improve their images: Don’t let your top executives skip out on a speech by the President. It’s a simple suggestion that is apparently news to many bankers whose absence from President Obama’s speech to Wall Street on Monday has not gone unnoticed.

Writing for the New York Times’ Economix Blog today, economist Simon Johnson points out that “not a single big bank chief executive apparently had the time to show a little respect or gratitude, and even to pay lip service to better behavior in the future” by attending the speech Obama delivered in Federal Hall, across the street from the Federal Reserve Bank of New York.

“Perhaps the chief executives of our biggest banks have instead weighed the man and done the trade,” Johnson writes. “It seems they may have moved on — presumably back to whatever they were doing before the events of September 2008 so rudely interrupted.”