Interesting and provocative subject but I think the examples cited in the OP don't support the premise. Doc flew home to Orlando constantly to watch his son play high school ball, not because he wasn't comfortable here. Danny didn't draft draft Olynk because he was white, he thought he was a skilled big who fit Brad's system (and when inspired, he did). Fans wanted Hayward to replace Crowder because he was a much better overall player (although I'm not happy with some of the abuse Crowder caught online). Danny didn't trade Hayward when he was hurt, because nobody in their right mind would have acquired that contract after such a devastating injury. IT, on the other hand, was dealt for a younger, better all-around player and was expected back by the all-star break, if not sooner, at the time of the trade (although Boston's team doctors may have thought differently).
With that said, racism in Boston, and in America, is not a thing of the past. Marcus Smart has experienced it at TD Garden. Adam Jones was called the N-word at Fenway. John Salley recently said that literally every racist experience he encountered in the NBA happened in Boston. (He said the Pistons had only one restaurant in Boston they felt safe eating at.)
And what happened to Bill Russell was despicable and should never be forgotten.