Bill Kristol said that there were lots of debates within the White House about how feisty Bush should be on various issues such as Alito's confirmation hearings, making the tax cuts permanent, etc. And, as Kristol said, "the squishes won." So, Bush came off as rather conciliatory.
That might not gratify some of the more aggressive of Bush's supporters, but I think it's just the right tone for a State of the Union. That isn't the time for partisan attacks.
That makes the contrast between the tone of the President's speech and Governor Kaine's response so much more noticeable. Kaine's whole point is to criticize everything the administration does or has done. That's the whole purpose of the opposition response.