If the Democratic line on Obamacare/ACA of "Fix Obamacare, don't repeal it" were more than a poll tested platitude, Senators and Congressmen in that party would be coming out with reform bills, essentially punchdown lists, that purportedly fixed the legislation so that the system ran better. We would have a crystal clear idea of what the Democratic members of Congress actually wanted to do to fix this program.
Currently, we don't have such bills in front of the Senate, where Democrats could put one up even if the GOP were being entirely obstructionist. We also don't have any such bills bottled up in committee in the House.
What we do have is a nice media campaign that doesn't actually serve the interest of the american people at all because it's all empty words.