The Abandon Adventure question buttons currently appear after the player has started an adventure, returned to the map, and selected a different location. I think it would work better if the question appeared when the player has begun the adventure and selects 'Return To Map'. It would eliminate the need for the 'blacked out' map now displayed upon return, and allow the player to select any destination. I can't think of a reason to return to the map from an adventure in progress except to abandon the adventure. Asking the question when 'Return To Map' is pressed would allow a do-over if you hit the button by mistake, and prevent time spent loading the map then reloading the dungeon. It would also simplify things for the farmers.
Can't you go buy things in a shop when returning to the map from an adventure? I assume that is the reason for this -- they want new players (who may not possess an item with key cards that would make the mission they're stuck on) to be able to go to the store and buy it without having to restart the mission.
Weird. I don't understand the purpose of that, then. Can you play multiplayer? What can you do? I never really experimented with it.
What don't you understand the purpose of? Several different specific things have been talked about here.
I don't understand the purpose of being able to view the map without leaving an adventure. (I checked, and you can enter multiplayer, but that seems to be all you can do.)
I don't see much purpose to it either. I guess you can view the other available adventures in case you decide to switch adventures in the middle of one. Why this needs to be possible without leaving the adventure, I don't know. Maybe an argument could be made that if you're stuck in a difficult SP battle you can go to MP to win some new items and then return to SP without having to completely restart the adventure (you'll still lose one try), but I feel this is such a rare edge case it's not worth keeping the current functionality for. Come to think of it, you can probably go to a shop without abandoning an adventure by going to MP and shopping from there. Still, I'd argue that if you know to do that, you're already such an experienced player you have no need for the convoluted possibility. It's not exactly obvious or advertised, is it? It's probably an unintended emergent affordance at best.
I suppose they left it in for a reason. "I'm getting tired of this particular level at the moment, so I'll probably cleanse my palette with some multi-player and come back to complete the map later."
Perhaps. A player can't change party members, but can buy and sell in MP shops. I've been a dev on other games, and sometimes things like this just slip through. On the other hand, it could be intentional and would explain the current setup. We won't know until they tell us, and they may have to determine whether it's a bug or a feature first.