Democrats have failed to win contested seats with their current platform. They've lost on epic proportions in recent years (the Presidency, House, Senate, Supreme Court, etc.). Obviously, they're doing something wrong. Why not give Bernieism a shot? Appealing to blue collar voters (their New Deal Era base) and increasing millennial turnout doesn't sound like a bad idea.
But acting like a full-blown SJW (like Bernie and Warren) is a massive turnoff.
What leads you to believe that? Just because they're liberals doesn't mean they're SJWs. A SJW is someone who tries to limit free speech. They believe people shouldn't be allowed to say things that could offend others. That definition certainly doesn't fit Sanders and Warren. Back in April, Sanders condemned college students at UC Berkeley for threatening conservative speaker Ann Coulter. He is quoted as saying: “Obviously Ann Coulter’s outrageous ― to my mind, off the wall. But you know, people have a right to give their two cents-worth, give a speech, without fear of violence and intimidation.” In another instance, 2 BLM activists interrupted Bernie Sanders during a speech in August, 2015. Although he was clearly upset, he gave them his microphone and stepped aside.
http://www.huffingtonpost.com/entry/bernie-sanders-ann-coulter-berkeley_us_58fb7006e4b00fa7de14bc3dhttp://www.nbcnews.com/politics/2016-election/black-lives-matter-activists-disrupt-bernie-sanders-speech-n406546