Wholeheartedly agree, but I think it's worth mentioning that few whites polled today will have accurate memories of the 1950s as a whole, and many polled were probably not alive during the 1950s at all. 
When they speak fondly of the 1950s, they likely do not even consider the evils against people of color, dissidents, women, sexual minorities... They mean a cozy, safe world without the stresses of 2016. 

People of color who think of the 1950s will - with good reason! - first think of the racial atrocities committed at that time.