You can build alot of it with the tiles that are alraedy there, but I agree with you that a dedicated dungeon asset would be great and i have it planned for a future pack.
Im not sure what the next pack will be yet. I've gotten some request for a orc faction package with orcs and goblins etc. so perhaps something along those lines for the fantasy series!
+1 for me. Orcs/goblins/gnolls/kobolds all these humanoids fantasy monsters would be amazing and I would definitely prefer to see those rather than the indoor tiles :D
