One, it essentially kept Clinton on the sidelines just two days after her big West Virginia victory. Two, Obama’s opponent was no longer Clinton or McCain, but the man with the 27% job-approval rating.
And then there's this, which is both important in itself, and a sign of the tactical complications Bush could pose for McCain throughout the election:
But we have to ask: Did anyone in McCain's orbit get a head's up on this? After all, Bush’s remarks -- and then McCain’s response to them -- overshadowed McCain’s big “2013” speech that he gave to put more room between himself and Bush. They also undercut that very speech after McCain essentially agreed with Bush’s assessment. As the Obama campaign pointed out, McCain delivered “a lofty speech about civility and bipartisanship in the morning, and then embrace[d] George Bush's disgraceful political attack in the afternoon.”
Presumably this is fixable. I'm guessing the McCain campaign can call the White House and tell Bush to knock it off. Or at least to coordinate better in the future. Back when he endorsed McCain in March, Bush did suggest he'd be willing to lay low if that's what McCain wanted.
But maybe not. You obviously can't make the president go away completely. Maybe Bush, in his own way, ends up being the kind of unhelpful freelancer with a direct pipeline to the media that Bill Clinton was during the primaries.