I do know what you mean. I am planning to eventually create a "NPC" account. However, I am not planning to reply to every single mission. I have a lot of works outside the forums, so RPing with everyone doing a mission would be simply impossible, especially since I'm extremely poor at managing my time!
This NPC account will serve for two purposes:
-Important interactions with NPCs in town. Currently, there's two NPCs: the one at my Library, and the one at the Explorer's HQ. The one at my Library isn't important, so a player can take control of him. The one at the Explorer IS important, so I'll control him.
-Important NPCs in events. Not the regular baddies, but the Boss of those baddies.