I don't think keeping people angry has anything to do with it. There is nothing wrong with people being concerned about high crime, no matter how it is in relation to the past. No one can say that the areas people are talking about has low crime rate; thus, the need for conversation is definitely okay. Deflecting by saying, well it is lower than a previous time in history does nothing other than to deflect and/or argue with people. If you don't think there is a problem in the areas in question, you may in fact be part of the problem.
Again, what are the things each of these areas have in common?