Gotta give credit where it's due - not just for Streisand, but for a lot of the Hollywood left. Many of them are brilliant actors and singers, but like you say - once they stop acting/singing/whatever and start talking, then they completely lose me.
And to be honest, I don't like listening to politics of any kind from entertainers. Just because they're in the entertainment business doesn't give them any extra credibility in my view, and if I want to listen to political opinion, there's all kinds of places to get it without listening to entertainers spouting their often-idiotic views.