Here's a pretty decent article in re: the flag.
http://www.theatlantic.com/politics/archive/2015/06/what-this-cruel-war-was-over/396482/
As for Crazy Horse...maybe his monument will be bigger because his people were here first? I don't know, I'm just spitballin' here. Sorry, that's being flippant, and I don't mean to.
What's complicated about the issue is this: This is America's history. We are Americans. And some of the things we did while shaping our nation are really terrible. That's uncomfortable. No one likes to hear about how they fucked up. But all nations' histories are rife with mistakes. What feels best, to me, in such situations is to apologize and move on. Maybe that's what all the hubbub is about...formally apologizing, so we can move on.
Shit man, we're all a bunch of imperfect humans, perceiving our existence through the lens of our own feeble brains. And all our ideologies are truly the curse of humanity. Religions. Nations. Borders. Governments. Once we think we know any damn thing -- just you watch out -- we're gonna defend our ideas to the death, break our own god's rules...for our gods!!
Sometimes I lose my keys. I'll say to myself, "I know I put my keys right here...I remember doing it...I know for a fact I left them here..." Then I'll find them in my jeans and remember, "oh, shit, that's right...I put my keys there yesterday, not today." And if I can be wrong about that, I can be wrong about anything. Including an ideology. Or ALL ideologies. We each arrive at a belief system that gets us through our days as painlessly as possible. But I don't trust that my "truth" is anything more than the prejudices I agree with. And neither is anyone else's "truth." We're all insane. I just want to live my crazy days out being as decent as I can to as many people as I can.