Hillary needs her feet held to the fire before the election. Democrats need to pressure her to be more liberal or it isn't going to happen
If the issues you care about are trade and weed, she's already said that she wants to reclassify marijuana, which would be extremely important to states that legalize marijuana. Trump has said no such thing.
Hillary's platform (and history) is far more progressive by any standard compared to Trump's. That's not to say she hasn't had missteps, but to even argue that Trump is "to the left of Hillary" on economic issues flies in the face of logic and history. And, their platforms that they're running on.