If you can't, won't or refuse to talk about the present, you have to bash the past to distract. Explains why a ton of past bashing is going on. "Keep reminding how bad it used to be by avoding how worse you made it to be."
Their accomplishments are not popular and were accomplished in spite of the majority of American people. That's what happens when your policy is about ramming things down people's throats when they don't want it.