Dick Morris nails it every six-months or so:

Democrats are determined to make the political cost of this war more onerous and burdensome on the Republican president. By harping on the need for more manpower, they build the pressure with each combat death. If the Democrats can sell the proposition that more troops are needed, they can force Bush to move toward conscription to fill the ranks.

Fortunately, Hillary's visit was drowned out by Bush's voyage to Baghdad. The liberal media tried to couple the two visits. The New York Times' headline was "Hail to the Chief; Hail to the Senator." But the visits are hardly comparable. Bush's was designed to raise morale, Hillary's to raise objections.

Bush sought to assure the troops of the united support of the people. Hillary wanted them to know that many people objected to what they are trying to do.

Bush's message was that we will persevere in the face of terrorism. Hillary's was that this war was due to one man's "obsession."

Sen. Clinton will do anything she can to attract attention and, where possible, divert it from the Democrats who are really running for president. But this trip, at this time, in this manner, in that place was wrong politically and morally.

Hillary had made it a priority during her stay in the Whitehouse to belittle the military, and believe me, I was in at the the time, they know it. Look at the pictures and read the stories, they hate her.
The press is all over the Bush visiting PR story, but the public knows that Bush was doing what was right and it was required.