I think what you mention may be Crystal's reason why they are so consistent. 2 ships, and you can reasonably expect a consistent level of service when you have 2 ships. The staff turnover will be lower, you can expect to find a large percentage of the same staff on the same ship. I think they have less supply and more demand where most lines may have the opposite. It seems Crystal is building the Serenity for a reason, not just to keep up with the "we have new ships" Joneses.
I think the building boom has hurt the industry. When Celebrity had 3 ships they were fairly consistently on a high level. Things started to change with the addition of the next 3. When these ships started to bring a decent level of consistency, though of a lower standard than the original 3, then 4 more came, larger and within a smaller amount of time than the middle 3 ships.
So, I think if Celebrity gets real with itself and addresses core problems, then the line can begin reestablishing its standards in food, service, and working at consistency. And the first has to be the "wow" that Babette speaks of, the second has to be on a level that consistently outperforms at least the mainstream lines.
I think, ultimately, the new has to come in new aspects of cruising rather than new ships with more amenities and land-based type of features. The "something" that makes a shipboard experience unique is being missed by the upper management, I think, is to make a more distinct cruise product, and take advantage of particular aspects of ship design vs. scaled resort/hotel design that I feel is compromising ships. And I also think that recognizing the finite amount of people that want cruise vacations in the long-run, vs. those that want to try cruising now on a new ship but won't be around in a few years when the ships are older, and dealing with the finite, smallish market, at least for those that want a standard that HAL or Celebrity claim to provide, and making that product profitable, yet reasonably affordable.
The market is still soft, and the industry overbuilt. We'll see what happens with the quality and consistency of lines like HAL, Celebrity, and Princess when the market becomes more robust. The danger is, by this time, these lines will be just middle-America, mainstream lines, and Oceania and Radisson will become the new premium lines.