I don't understand any of the arguments against it tbh.
30 hours a week might be too high, because it does take time if you are seriously looking for work, but other than that, of course it's a good idea.
The ones I would feel sorry for are the charities that then have to manage this. If they are provided with ppeople who are eager to learn and have skills of some sort, fantastic. But if they are provided with people that don't want to work, and don't want learn new skills that will look good on their CV then it's going to be a nightmare for them.
Years ago when the New Deal for Lone Parents came out. I was working at a small charity, which had 6 employees, but they simply wouldn't have have been able to survive without it's volunteers. The volunteers did loads of reception and admin work, looked after the charities disabled beneficiaries by getting them drinks, helping with lunch etc, so that they were ready for the treatments that the employees provided or so that they weren't left starving while they waited for transport home. We had a girl come to us on the New Deal, and it simply didn't work. she was constantly having childcare issues, and the paperwork and job centre visits around the whole thing made it really hard for her. As a result the poor girl was completely drained and it sucked all the enthusiasm she had out of her. Plus the endless form filling in that the regular volunteers had to do for her made thei job even more difficult.
They will have to arrange this system very well for it to actually work and somehow I don't trust the government to do that.