Both things can be true. Rondale Moore can fill the role of a credible change-of-pace and third-down back, and we could still need a credible second back who can carry the load for a few games when something happens to James Conner to sideline him for five games.
@Chopper0080 is on the right track, I think, that RB is a category where you can get a lot of value for a little money. I don't know why he'd want to come here for that much, but if King Henry wanted to come here for the same $5 million cash salary that Conner is making, you're probably better off doing that than investing big in a WR room that Kyler won't throw to.
Would you rather have Hollywood Brown for $14 million or Derrick Henry for $5 million?