Littleton played 94% of the snaps last year, top number on defense, and he's gone. (Weddle: 93% & AD: 84% were second and third). I think the Rams would have loved to extend him, but economics prevented them from doing so.
Rams may have the same problem with JJ. Tons of 'want to', but not enough cap space. And with Rapp, Burgess, and Fuller (and Scott? plus JR Reed and JuJu Hughes on the practice squad) the Rams are actually in a better position if JJ walks than they were when Littleton left.
AlbaNY_Ram