I wonder if the primary issue might be modeled this way:
Some gamers (DM's and players) view players as consumers. The DM produces a product, the players consume that product and play progresses. As consumers, the players are not expected to have a significant amount of input in what the producer produces, so long as the consumers are happy with what is produced. The players come to the session, play during that session and once the session ends, they don't play again until the next session and have very little interest in the production side of the equation.
Other gamers, myself among them, view everyone at the table as collaborators. Sure, the DM is likely going to do more work than any single player, fair enough. But, the players expect and are expected to contribute outside of the game. During play, sure, we play in character and whatnot. But, once play stops, the players put on their contribution hats and supply various elements - NPC's, possible connections, discussions about the future direction of the campaign, goals etc - to the campaign.
Does this make sense? If you're a "Players as consumers" type DM, then, player input isn't really sought or expected. You have your campaign, your world and the players can take it or leave it. OTOH, if you're a "Players as collaborators" type DM, not only do you welcome player input in the design of the campaign world, you expect it.