The Democrats have a hard challenge. The leader of their adversaries has a much stronger pull on his base than the D's on theirs. This leader can say, at any time, "Occupy Federal Buildings" and the USA has 100 Waco-like situations. This threat is affecting the decisions of the D's. It's hard to run a 100-meter dash through a minefield.

Having said that, the D's are playing to their demographic just as you have said, relying on other demographics to vote D anyways.

The system is screwed up. It's time for Americans to build a new democracy:

https://medium.com/discourse/tiered-democratic-governance-3f36a8f45660