"I understand about retrospective studies but it seems that if pervasive patterns are found, they should at least be acknowledged. Nobody suggests that he's got a crystal ball."
Most of the time economics IS most important in elections, but not always. There are still some things that trump economics. I suspect that the public would still not reelect an incumbent male President presiding over an economic boom if he were publicly shown to be in bed with a dead girl or live boy (though I'm not certain about the latter). There are still some outer bounds of behavior that even our jaded electorate will not tolerate, even in boom times.
War also has the ability to trump economics, I believe.
So do I. Depending on the character of that war and whether we are perceived to be winning. Lincoln was convinced he couldn't be re-elected until the victories at Vicksburg/Gettysburg, followed by Sherman's taking of Atlanta just before the election. Johnson made no effort to enlist public support for the Vietnam War, defaulting to a pro-communist media which crucified him. He became so unpopular he didn't even bother to run for re-election. Now we're engaged in a diffuse, unconventional war that is likely to be protracted over a period of decades. This is a much more difficult sell, especially with the media doing everything possible to lend support to the enemy, at times practically denying that there even is an enemy. Sherman considered reporters no better than enemy spies and sometimes treated them as such.