When the Rams are in their 1 TE, 3WR set they typically face nickle or dime defenses. The Rams obviously have success passing out of this set. They also have success running because the Rams' WRs are pretty good blockers, but also because Gurley is more likely to face a DB at the second level than a LB.
If the Rams went with 2 TEs the Chiefs would counter with their base 3-4 defense. They'd end up with Everett trying to block a LB instead of one of the WRs blocking a CB ... and Gurley would face another LB (or 2). Might be more 8-man boxes, too ...
IMO the 2-TE set (or putting 2 RBs on the field at the same time) diminishes the passing attack without really helping the running game much (if at all) considering the D they would face.
AlbaNY_Ram