We have moved beyond subsistence farming and free food - "food on the table" means a lot more, including many scarce goods.
You want tobacco? Go and work for it. You want booze? Go and work for it. You want PS3? Go and work for it.
Isn't this how food stamps are currently supposed to work? They only cover staples, and users aren't allowed to pay for tobacco, etc. The thing is, in the real world, food stamp recipients frequently barter their vouchers for these luxury items.
When considering such measures, we need to stop imagining what an optimal government might be able to do. Instead, look at the history of such efforts, and the incentive structures (consider Public Choice economics) to understand what is likely to transpire.