Her voice is quavering, as if she's on the verge of tears the whole time, yet still pretty genuine. Lots of good images of military families, night-shift workers and parents with children. This is Hallmark TV at its best. (Which, to be clear, is still not as good as HBO at its worst.)
It's possible that the calculation was that they had to present her with a soft image, and so they couldn't have any red meat on her night -- that it was worth sacrificing a night to have a knockout Michelle Obama speech. Who knows? Maybe it's worth it.