Matt Yglesias explains why War with Iran is a bad idea. He also brings up the possibility that all of the hawks who insist on the non-necessity of an occupation to midwife the birth of a new Iraqi government might be trying to trick us into getting committed (and then when the occupation is necessary, tell us that it's too late, we have no choice).
Likewise, Jim Henley suggests that the whole idea of attacking Iran next is designed simply to be a raw and vulgar display of Yank power.
All of which is why bringing up mistakes that were made in Iraq is agood thing, and not merely "living in the past." It's important to force attention on our previous mistakes when we are about to make them all again.
That is all.