I think that's a good reason for the RBC approach. And apparently the Rams agree with you.
Henderson (who has not missed a game this year) has averaged 9.2 carries a game. He has exceeded 15 carries only once: week 3, against the Bills, when he got 20 carries for a season-high 114 yards.
Akers has missed 3 games this year, weeks 3, 4, & 17. In addition, there were two games where he played but didn't get any carries: week 6 (SF) and week 7 (CHI). In the 10 games he did play he has averaged 12.4 carries a game. He has exceeded 15 carries twice: 21 carries in week 13 (ARI) and 29 carries in week 14 (NE) when he got a season high 179 yards.
AlbaNY_Ram