(As some people noted, it would not have made sense to re-introduce Merry & Pip as players. Each of them goes off on his own. It would have made a three-way party split, which is confusing enough. Worse, most of the humor comes from the players ignoring NPCs and talking to each other – something the Hobbits wouldn’t be able to do. I could have made them players, but I couldn’t make them funny.)
NPCs do enjoy such an odd status as second-class beings. Players will talk amongst themselves as if the NPC wasn’t there. Players will walk away in the middle of a conversation if they realize an NPC is of no use to them. Players expect NPCs to be available at their whim to provide information and dispense rewards. This applies even if the players are nobodies and the NPC in question is a King. In fact, if NPCs ever turned the tables and treated players as they treated others, it would most likely lead to violence.
This is as it should be. Imagine how tedious a story would be if every extra and minor character you encountered tried to shove out in front and make themselves into a main character.
Nobody wants that much realism.