I don't think that there are negative issues with the market per se, as it's a rapidly growing one with a growing middle class that enjoys vacationing, it's just a very different market for cruising. Also, keep in mind that Asia is a massive place and what most people mean by "Asia" is "China" and, to a lesser extent, Japan. Chinese cruises tend to focus heavily on gambling, for example, which is distinctly un-Disney, and smoking is culturally acceptable and expected. In other words, if
DCL did base a ship in China, and adapted to the expectations of that market, most Americans who travel there for a cruise would be surprised and, possibly, disappointed. It would likely not feel like a traditional DCL cruise just relocated to a different continent.
Here is an interesting--positive and balanced--article about
RCCL's experience that gives a good perspective:
http://www.miamiherald.com/news/business/tourism-cruises/article131951214.html