Experience and education breed cynicism. In Bush, we perceived a man who displayed few mannerisms which are associated with the elite and educated. For this he was chided. In Obama, we perceive a man who displays many mannerisms which are associated withe the elite and educated. For this he is chided. At similar points in their respective presidential campaigns, they both have made calls for Americans and particularly politicians to embrace virtue and throw off partisan politics. Certainly both men are very politically aware, but I don't believe that sermon was insincere by either. I believe both truly want(ed) to embrace a unified, single-minded, virtuous goal for the country. The difference comes from the context in which that impetus is found. One expects naiveté from the grammatically incorrect and the simple-minded, so when you hear them speak of virtue, it is easily dismissed. One expects cynicism from the educated and the elite, so when you hear them speak of virtue, it garners more attention. The fact that we are being called to virtue by one who is, assumedly, well-versed and wise gives his words a different hue (no pun intended).
Perhaps with experience, he will shrink from his assertion: "...we reject as false the choice between our safety and our ideals... Those ideals still light the world, and we will not give them up for expedience's sake." So far, it seems he has not. We'll see how long that lasts.