I've already posted about how the (Chinese) main character of Dragonball Evolution (my title: Dragonball Retrogression) was given to a Caucasian actor, but apparently almost all of the main roles of another clearly East Asian-derived fantasy movie, The Last Airbender, have been given to Caucasian actors as well. This brings us to the Unwritten Rules for Casting East Asians in Hollywood, as follows:
1. (East) Asians may not be cast as leads in any movies, even specifically Asian ones, unless they are Jackie Chan or Jet Li (other Asians who happen to know kung fu unfortunately do not count). This is good because Caucasians with hair dyed black look exactly like Asians and can hardly be differentiated (pure genius!) - so basically, we don't need Asians in movies (except for Jackie and Jet).
2. Asian males are not allowed to have kiss scenes (or (gasp!) love scenes), ever, even if they are Jackie Chan or Jet Li, because that would be offensive. (Asian females are allowed to have kiss scenes with Caucasian males, however, because, you know, that's cool.)
Basically, this means that Asians may only be cast as:
1. Kung fu masters (but only Jackie Chan, Jet Li, or a few others. Being Asian (even Chinese) and learning kung fu does not give you this right. Females get it a bit easier here).
2. Yakuza/Triad members or otherwise shady characters
3. Dorky/horny/harmless buddy-type character
Now, I know that Hollywood is afraid that casting Asians in its main roles will make its movies automatic failures - this is understandable, as Asians are of course lacking in attractiveness and coolness and all that; I'm not blaming anyone. Heck, I've never even watched the Avatar TV show even once - although I am glad that they based the main character's martial art on my own favorite martial art, baguazhang. I do think that they could have at least given a few of the main characters' roles to Asians (heck, the usual rule is that Asian girls get roles while Asian guys don't) and helped a few starving actors break their fasts and get some roles for once.
These last 10 years or so, I do think there are slightly more Asian actors in movies now, but only a little - it would be nice to see more progress soon.