Responding to the question of where to draw the line:
I preface this by saying I am strictly anti-pvp.
For me the line would be if the content effects any non-pvp content at all (such as tradable items/flow of money through the game as stated in the post) needs to be an open poll. Anything that is completely, 100% contained within the PvP community would be a-okay with me to just ask PvPers.
Edit: Also, I'd add that if the change affects the wilderness in normal worlds, even if the change is PvP only, it should be polled to everyone. PvMers and skillers have to use the wildy for some of the content, so it's not fair to them to just ask the PvPers. This post was more for the idea that it would only be on PvP worlds.