ITA about the Knierims' skills when they are fit and in-the-zone, but they have been coming back from a lot in recent seasons, so hopefully they are healed and ready to skate the way they can more consistently in the coming season. I wouldn't say that their chemistry and unison are better necessarily than K/O's and C-G/LD's. Also, D/F have a bit better lifts and equally good throws.
I have no insider knowledge regarding US fed's favoritism in this case, except to say it's obvious the Knierims are and have been favored, but probably largely in part for their valuable skills, as you indicate, even when they haven't performed well.
ETA:
What's really going on with the roadblocks to Deanna & Maxime partnering? Does anyone have solid information?