Operation Crimson Hammer is more so a optional dlc not an expansion pack, no disrespect. It is optional enough that a player can typically progress in the game to the end without ever knowing Operation Crimson Hammer existed from a game play perspective.
A expansion worth buying is one that "expands" or moves the game forward. Here is a short list of features I would expect.
- A new tier of levels.
- New 6 or even 7 star alchemy paths.
- New items.
- New monsters.
- A new path for the shadow lair based on the new tiers.
- At least one new game play mechanic that adds more depth to combat. This could be anything from adding a new element to adding a new type of weapon.
Now I do not really know anything about the development limitations of this game so I can't really say how reasonable or realistic my suggestion will be from a developer perspective but in the least it is what I think would be a real expansion for this game.
A new set of levels that offers new weapons seems like an expansion to me, whether you have to pay or not. 6 and 7 star items are a terrible idea, first of all, they are awkward numbers, and, in my opinion, a new type of weapon like master weapons should come with the core update. (they require a great deal of wealth and hard work). Also, they have to set up their DLCs wisely to not make FtP players seem too inferior, if some of these were aspects of a DLC, players who are not committed enough to pay will be by far outmatched gear wise, and entertainment wise. This game is mostly free to play, and I don't want it to turn into a normal MMO where you have to spend tons of money to be good or play the other half of the game.