I know I'm parroting what some people have already said before, but DAMN wandering merchants are a horrible addition. Why? I can't get sangomon to appear for some reason and ONLY shortmon is appearing, and it takes an absurd amount of time to even get a wandering merchant to spawn. It's become near impossible to get madicmon because of this, since I only need sangomon left. This also makes it impossible to finish other quests, like kudamon and minomon. Needing RNG npc's to get other npc's is absurd in my opinion, since I've basically been screwed over by the gods of luck. I literally cannot finish server city because only shortmon is appearing.
I'm not saying to completely remove them, but the least that could be done is making it so that you can't get the same wandering merchant twice in a row, which would make it so much easier to complete medicmon, and by extension other npc's.