Whitewashing in Hollywood: The Race of Kahn

In the older films we have watched and studied in this class many of the problematic portrayals of race have been explained as at least in part, by the explicitly racist cultural norms that persisted during the time of their production. However, a number of high profile racial casting decisions have revealed the persistence of many similarly problematic practices in Hollywood productions today. 

The controversy surrounding the recent blockbuster Star Trek: Into Darkness exemplifies a tendency in many popular movies to engage in the "whitewashing" of characters that would otherwise be portrayed as Persons of Color. 

Into Darkness was the second film in the new Star Trek reboot by JJ Abrams and a modified retelling of what is commonly considered to be the best Star Trek film of all time, Star Trek II: The Wrath of Kahn (1982). 

In the original movie Kahn (a genetically superior tyrant who briefly rules the earth and is hellbent on extracting revenge on the Enterprise and its crew) is identified and played by a POC. His race is important in both the context of the plot of the movie and the cultural significance of Star Trek as a particularly progressive media franchise. However in the 2013 reboot of the film, the decision to make Kahn white has drawn cries of whitewashing and racism from various groups. 

1982

Ricardo Montalban the actor who played Kahn in the original:

And here he is in one of the most iconic scenes in the film: 

2013: 

Benedict Cumberbatch as Kahn in Star Trek: Into Darkness:

Here is a scene from Into Darkness:

Reaction to making Kahn white in the film has focused on the decision as a prime example of how "Hollywood’s whitewashing is a systematic form of racism that fills out roles meant for people of color with white actors, [...] suggesting that Hollywood might be inclined to believe that it’s only white actors all moviegoers want to see on screen". 

Although these critics of the new Star Trek franchise recognize the imperfect casting in the original film admitting: 

"It wasn't perfect in the 60s when Ricardo Montalban was cast to play Kahn (a character explicitly described in the episode script of Space Seed as being Sikh, from the Northern regions of India)". 

They justify this by pointing about that: 

"Considering all the barriers to representation that Roddenberry faced from the television networks, having a brown-skinned man play a brown character was a hard-won victory".  

What might contribute to this ongoing practice of whitewashing in Hollywood entertainment? 

Are the motivations driving these modern decisions any different from the whitewashing practices in older films such as Pinky? If so, what differentiates them?