So what you're saying is people should make films that don't appeal as much to their target audiences? Do you know how stupid that is?
The vast majority of western cinema goers are white. The majority of western inhabitants are white. Ergo when a film is set in the West or targeting a western audience it makes sense for the majority of the characters to be...white. it helps the viewer relate more.
Or are we going to start proposing that Bollywood films should be full of Latinos and Inuit?
Not at all, I completely understand why producers would feel the need to mandate that a film like Deathnote be moved to a western setting, and I think you're right the setting of a film and potentially the race of its cast (not necessarily individual characters but entire casts certainly) has an impact on whether or not people will go and watch it. Having said that films like Crouching Tiger do suggest that this isn't always the case.
I still think it's a bad reason for moving the setting though, especially since it's had a negative effect in my opinion on what the film could have been (and keep in mind I've never seen the anime etc so that's not a factor for me). The way the film is shot and the general tone would have been a brilliant fit for a Japanese setting, especially Tokyo. At what point does the creative damage of pandering to the audience in a quest for ratings overrule the benefit of doing so, what's more relevant, having a commercial success or a critical one? It's a fine line certainly.
The problem with this kind of re-imagining is that, unless audiences are given the option of experiencing an adaptation involving the true setting, then they'll never adapt (if a period of adaptation is needed). It's a chicken and the egg scenario, big studios can't throw out AAA films that take these kind of risks if they can't be sure that people will watch, we won't know if people will watch/people won't gradually embrace the changes unless we create the relevant AAA content.
I get the concerns, but part of me thinks if your film is good people will watch regardless of the setting and race of cast members.
Your last point is nonsense, Bollywood films are inherently culturally Indian and as such should retain that cultural identity, it's exactly the case I was making for not moving the setting of certain films.