McCain is in a box. "Reaching Across the Aisle" is a major theme of his campaign. That means he doesn't want to attack Democrats. He can attack Obama but he can't attack Democrats in general because he is hoping to attract enough of those Dems in the Undecided/Independent group to get himself elected.
Same deal with talking up the roots of the financial crisis. We all know that those roots lead you right back to Bill Clinton and his push for "Affordable Housing". You may recall that Bill Clinton is married (sort of) to Hillary Clinton whose supporters are also targets for a McCain vote. McCain is therefore unlikely to go after anyone named Clinton even if we here at FR are begging him to do so. Not going to happen IMHO.
If I expect a fellow American to defend my country, who may give their all, then is less expected of me? I would rather see our country blessed and free than enslaved by socialism. It is crystal clear that the Dems are taking us down that path.