That is keen observation, that I would like to expand upon.
Bob Dole, Juan McCain, and Mittens Romney were each the hand picked choice of the pubbie elite and very weak candidates running against candidates that were very vulnerable.
Dole and McCain in particular were no cowards on the field of battle and each guy had no problem going on the attack in the primary, but in the general election that were appeared to be cowards to go on the attack.
Of course, Mittens had no military service record, his service record was in missionary service in which he went out pestering people with the Book of Mormon. But as you pointed out Mittens was had no qualms with bringing Bob Dole out of the nursing home to attack Newt in a trumped up paper interview if not one in the flesh.
Romney's defining moment as a candidate was the third debate. He was unwilling to attack Barry with the truth of Benghazi when Barry had attacked him with every lie in the book.
Mittens was an idiot just like Dole and McCain because they listened to the liars in the MSM who say that women voters do not like negative attacks.
Once again that is a lie, Barry ran what probably is the most unfair, dishonest and negative attack campaign in American history and women seemed to be all right with that.
Mittens played it safe because he believed the all the conservative know nothing commentators who said he had a lead and played it safe.
Mittens was not man enough to be president, you cannot reserve your strongest attacks for Newt Gingrich your primary opponent, get pummeled with lie after lie in the general election, and then have the truth of Benghazi handed to you on a silver plate and refuse to use it.
Notice how gallup had it even at the end.