How about human flesh? Nuclear waste? Bombs? Bags of dangerous quantities of hard drugs [a la drug mule]? Endangered species?
Just like with free speech, "do anything you want for any reason" has the potential for abuse (both by a person to themselves and by other persons to other entities), and the majority of society is not comfortable with that. Sometimes we can be indoctrinated into tacitly accepting it after intense special interest lobbying, such as with handguns and cars. But there's probably no "greater good" aspect of being able to eat literally anything.