I've heard some people (mostly older white men) say that they don't find the "Redskins" name offensive at all. But KKK members were probably not offended by the N-word. They're not the targets of those slurs.
The best people to judge the offensiveness of a potential slur are the targets of that slur. In the "Redskins" case, Native Americans.
So I emailed a close friend who had married into a Native American family, and asked how her husband and his family feel about the term.
Her response was brief and straightforward:
"Redskin(s)" is derogatory and racist. Can you imagine any sports team named the N-word?
I rest my case.