In this thread I will explain why pve and pvp mixed is bad in fonlines and suggest some changes to the common settings.
When there is a risk that hostile players might spawn in your encounter when you're already fighting npcs it may encourage (according to some) interesting situations. But truthfully these situations are just bad gameplay that kills activity. If you can meet and kill players who do pve, it may increase player interaction but it KILLS the whole activity of pve. To make you understand here's an example of the illusion of player interaction: you might say that if there was a chance that players could find each other's bases on wm it'd increase player interaction but at the same time it kills the whole idea of bases.
If you make pve, you can't mix pvp into it because in encounters and dungeons pvp and pve are wastly different in terms of strategy. In pve you go against the npcs over and over recklessly. In pvp you camp, wait, scout and make brief offensive moves. In pvp you spend materials and have vague chance to get them in return, in pve you likely gain them at steady rate. Lastly, it's extremely stupid idea strategically to choose to fight npc and players at the same time.
If you lay a trap or seek your enemy from encounter, you aren't farming anymore, you don't get profits, you are wasting your time and there's a chance that you don't even find anyone. And even if you do manage to kill the guy who's harassing you, what guarantees you got he doesn't come back or come back with friends? Basically those who hunt down pve players ruin the whole activity in the area. Can't blame them because farmers are easy targets, so let's say that allowing this to happen ruins the activity.
So I suggest that where ever there are hostile npcs, there must not be chance that uninvited players appear. If there is a pve dungeon, then other players must not be allowed to enter that instance without some kind of invitation. If there are encounters with hostile npc, then players must be given a choice if they want other players in because maybe someone enjoys fighting npc and players at the same time.
You might think that all players will disappear in these safe farming grounds. Might be, but it's better than forcing players in situations they didn't sign up for. Forcing everyone to face pvp in unfair settings simply encourages avoidance. If someone wants pvp, then maybe he should stop looking easy targets and find actual pvp-oriented targets from pvp locations.