The left wing of the democratic party knows that corporate power must be challenged forcefully and directly. Many of Bernie's activists have decades of experience fighting capital and financial elites.
Everyone in the American Labor Movement knows that if your plan is to appeal to employer benevolence, you'll be crushed. Bernie's union supporters have firsthand experience battling companies engaged in brutal and malicious union-busting campaigns. The way you get a deal (and survive) is to up the ante. Let them know that you're willing to do as much damage and destruction to them as they'll do to you.
Bernie's campaign speaks to this strategy. A Sanders Administration will not dismantle capitalism but could redraw the lines. Many of Bernie's activists - labor, environmental, immigrant rights – know how to organize in the streets and in the political sphere. They may be a bit strident and ideological but they know it's a war.
Hillary Clinton is not naive about power relations. But she's too cozy with the bosses and, at best, would be a pest to corporate capital. After all, her starting point is to “incentivise” good behavior by billionaire elites. As if that would work.
Nevertheless, Hillary's campaign has some very savvy and sophisticated operatives - liberal and progressive to be sure - and she would likely be more clever and appropriately ruthless than Obama has been with our political opponents.
But she's too damn accommodating to global capital. Meeting them halfway on their turf is already giving away too much.