It would have been better if the benefits were limited to basic foods from the beginning.
However, you will find the main resistance to any change to come from huge multinational and vertically integrated food producers and distributors, and retail chains, who would lose HUGE amounts of revenue if food types were restricted.
Going back to the basics simply won’t happen short of a world war or something.
I know it won’t happen, but anyone who suggests food stamps should only be good for rice and beans would simultaneously neuter every Democrat argument. They could also argue it would lower the obesity rate.