as someone who knew Obama in law school, and now has observed his presidency, his avoidance of debate does seem to conform to a pattern. It has nothing to do with a gentlemanly or conciliatory reluctance to be aggressive. Rather, it has everything to do with a reluctance to be aggressive when his opponent is present -- where he can experience some push back from the person he's demonizing, and where his lack of preparation or knowledge can reveal him as foolish. (Hence, perhaps, the "decorous courtesy" in face to face encounters, where might prompt a more vigorous blowback.)
Think about it. There's never seen such a trash-talking campaigner -- one who accuses his opponent of lying, who allows his campaign to call Romney a murderer and a felon, one who calls Americans with whom he disagrees "fat cats," or accuses doctors of performing unnecessary surgeries. He has no problem going after Romney the day after the debate, when he's no longer there face-to-face, and when Obama's trusty teleprompter is back. In fact, President Obama is one of the least gentlemanly and most uncivil men to occupy the Oval Office -- certainly publicly (Richard Nixon's private utterances put him in the running, too).
Notice that the only time Obama apparently shrinks from throwing a punch is when his opponent can punch back. That's not a guy who's just too "conciliatory" to get down and dirty -- that's a guy who's afraid to get down and dirty when it means he might have to suffer the consequences.
In my book, that's what's known as a "bully" -- full of big talk in the locker room (or on Letterman) . . . but considerably less cocky when he actually has to address his opponent face to face, unprotected by the friendly aid of the MSM.