Having some bench RB's is obviously great for injuries and trade bait, but I wonder if they are even more important during playoffs.
For most leagues, all of the marbles come down to single elimination at the end of the season. And late in the season, some teams don't care in real life, which really kills in fantasyland. Is it wise to hang on to quality bench players in case your usual starter is on a team that has already secured it's playoff position?
Depending on the settings, this philosophy could apply to other positions. For example, my league starts 2 QB's, so most starting QB's are owned and the WW is bad. But for most every league, every starting RB is owned and if your stud RB is resting during your playoffs, that could really hurt.