Workfare relies on the assumption that most people are lazy and just don't want a job or are claiming fraudulently while they make money working in the black economy. It assumes that many claimants will get a legitimate job, or stop claiming while they continue with their black market job, rather than continue claiming benefits if life is made uncomfortable for them.
Personally, I believe that most people would prefer to work in real jobs than claim benefits, and are claiming because they either can't get a job or because circumstances have conspired to prevent them from being able to work. But I'll accept there are a fair number of people - and we all know them - to whom the feckless scrounger description will apply.
But here's the point: Even if everyone on benefits was a lazy feckless scrounger, how would workfare solve the problem? It can't if you think about it logically.
Some people are going to be unemployable no matter how many sanctions they are threatened with. Whether it's a case of a long, criminal record, poor interpersonal skills, appalling punctuality, illiteracy - some of these people couldn't hold down any kind of job even if they were bullied into turning up for them. So what then?
Sanctions. It's all well and good saying that if people are not prepared to work they don't deserve any help, but think about what that means in practice. It means people with no money. No money means no roof and no food. Starving, homeless people have a bad habit of either begging or committing crime to meet their basic needs, or being so inconsiderate as to sleep in shop doorways or be found dead on park benches. Crime and social disorder increase - something that will affect all of us. Although committing crime is actually not a bad move for people in this situation, since at least in prison they'll have a warm, dry bed and a square meal three times a day. More than can be said for the unemployed.
You can judge a society by how it treats its unfortunates. I don't want to be part of a society where the feckless are treated worse than actual criminals.
And as for the majority of unemployment benefit claimants who are simply normal, hardworking people without a job, all this does is stigmatise and punish them while actively preventing them from following a path that could actually be more appropriate for them. It doesn't actually find them a real job.