I'm not one that says he needs to sit, but why is when ever "sitting" a player is brought up it implies permanent changes. Why can't it simply be to pull a guy (distribute his minutes to someone else the remainder of the game) who's struggling and simply doesn't have it on a given night.
I'm nothing more than a fan, but for the most part no one seems to mind when defenders are put into a game to try to maintain a lead, or free throw shooters/ three point line ups are put on the court when baskets are needed, or a guy is pulled with two fouls in the first half to avoid "foul trouble" before the half, but yet to suggest to pull a player who simply isn't hitting his shots that night is crazy talk.
IMO it's has nothing to do with loyalty to a player or "look what he's done for the team" mentality, but rather simply wanting to win a game on a given night. Sure you want your best players receiving the majority of the minutes game in and game out, but at what point do you just accept the fact that they simply don't have it that night and look elsewhere to generate their productivity.