Resting starters can lead to a sloppy performance and it's important the Cowboys enter the playoffs on a roll if they want to advance. The Cowboys rested a lot of players in week 17 vs Washington in 07 and went one and out in the playoffs. Play for a bye then you get a rest.
To me it would come down to just how much that rest would actually matter. Bernie can probably do decently; and we do want to find out about our backup RBs.