I propose that they need to make random dungeons...random. What I mean by that is that there is an endless amount of posts about DLC dungeons being included in the random dungeon queue, but what if they took a different approach to the random dungeon? You would still have all your non-DLC dungeons(and DLC ones as well) but none of them would be included in the random dungeon queue.
The random dungeon would be randomly generated....you could generate the map procedurally randomly drawing the boss arenas from a pool of a few dozen different arenas. The bosses(and regular mobs) would also be pulled from a random pool. This would allow some interesting combinations with X boss in Y arena, allowing different strategies to defeat the boss based on the landscape of the arena(being able to use LOS with pillars for example to block a given attack). I realize that you would have to design the pool of boss monsters in such a way to make sure that you could defeat them regardless of which arena they landed in.
The idea appeals because you could add bosses to the pool over time, or mobs, etc so you might come up with some bizzare combinations like the stranglers or dryads from vMHK being paired with the planar inhibitor from vWGT(or a similar boss), but essentially you would be running a new dungeon every time. True....visually doing it this way might clash as you made your way from one arena to another, but I think it could be a lot of fun...and no one would have cause to complain about DLC and non-DLC dungeons being grouped together...you could have 3 difficulties which would change the boss and add pools as well as give different rewards based on difficulty.