The most important presidential responsibilities are to use the executive powers to react to emergencies ,to direct foreign policy, to appoint judges and high executive officials, to direct the federal agencies to execute the laws...none of these involve proposed legislative goals or initiatives. The president's legislative powers are limited, campaign proposals are mostly dead letters, and specific ones probably lose as many votes as they gain.
We know from experience that trump will try to revoke women's rights, worker rights, voting rights, environmental actions, will appoint right wing activist judges, and will try to dismantle agencies like the EPA and the Education Dept. He will also accede to dictators like putin and Xi and erode U.S. alliances abroad.
Harris demonstrated just how easy it is to manipulate him, how weak his grasp of policy is, how completely his knowledge base is just a parroting of right wing media. These are the things that voters who can be moved by rational considerations need to know, and she made them obvious.