If the candidates are legally bound to follow through on policy then it's slightly better yes but there's still a lot of wiggle-room in terms of implementation. Lobbyists often find ways to sneak in convenient loopholes inside regulations. Policy-based voting won't solve that because the voter isn't going to have time to read the full law; it might be many pages. What will happen is people who don't work and have more time on their hands will be more active politically and will get better representation. I mean, it'd definitely be an improvement though.