I'm afraid I do feel that when an established character is played by an ethnically incompatible character, it is entirely pandering to the PC division, and not 'hey, we're living in the 21st century'. This is a pathetic piece of rhetoric that will not change my mind in any way.
If we really are as forward and enlightened as we believe ourselves to be, then we should have no shame portraying characters as they are, and not feel the need to cast a non-appropriate actor in the part.
One great thing about human beings is that they are all different. We are not all completely interchangeable at any given moment. I cannot run like a Kenyan sprinter, but conversely, I doubt many Kenyan sprinters can lift the kind of loads as an Icelandic powerlifter. Its a hard fact of life, but we are not the same, and so pretending to be 'colour blind' for the sheer fucking sake of it to show everyone how 'modern' and 'progressive' we are is just childish and smacks of societal insecurity.
Therefore, I do not want to see Jean Claude Van Dam play Bruce Lee in a remake of his life, and I do not want to see Mickey Rourke play Mr T. I do not want to see Samuel L Jackson play Stephen Hawking and I do not want to see the Norse god Thor portrayed by a black actor because it makes no god-damned sense!
None of these things do, and all it does is ruin my suspension of disbelief and tramples on the verisimilitude of the adaptation I am watching, all for the sake of a 'diverse' cast that is no longer diverse but bloody ridiculous.
The next logical step is gender roles - why not cast Bruce Willis as the sensitive blonde who requires an action hero to save her? Come now, we're modern and progressive and ethnic and gender roles apparently have no place in our society, so lets abandon them all together and make films that nobody fucking understands any more because nobody can tell who is supposed to be playing what.
What really bugs me about this though, is that nobody seems to consider the life the character must have lead to bring them to the point they are at when the movie starts. A huge black man probably faces a great deal of different challenges and bigotries to a skinny white computer nerd, and overcomes them in an entirely different way, and yet you talk as if these actors should be able to play their parts interchangeably - as if this wouldn't totally render the story pointless, incomprehensible and laughable.
It is the life experiences of a character that shape their nature and make us sympathise with and like them. If you assume that life experiences don't matter, and that we all have the same lot, as the fantasy-world the PC brigade live in would have us believe, then you suck out all the interesting elements of a story in one foul swoop. It is our differences that make things interesting, lets not forget that. It doesn't mean we're going to start another Holocaust.
Honestly Bob, I generally think you're better than this, but you've just taken the ultra-PC high-ground here. I agree with the rest of what you've said here, but I can hardly believe you're okay with a PC butchering of an established character. If you want a black god superhero, then they should create a new one and consider what challenges and events occurred in that characters life, don't go ruining an established character for the rest of us.