My guess based on the conversation between the two NPCs this episode is that if NPCs are treated like trash by the adventurers, they will simply stop giving quests entirely to a region. Mostly because they'll simply flee. If they aren't there to run the stores, city bank, and other function, the player city will become a dead zone where players can't accomplish much of anything. I expect this has already happened to the northern city, where they willingly killed off many of the NPCs and drove away the rest.
Shiroe's narration and the conversations between Henrietta and Maryell about the magic bag was quite telling as well. Newer players can't get any of the items that the high level players earned from the story mode of the original game. With the expansion, there are likely even better quest rewards now. Experience is probably also increased greatly from quests, like in any MMO.
It is in their best interest to continue to gain the favor of The People of the Land. You can't simply talk to them anymore and just instantly get the quest, you have to convince them now.