I'm not for banning that altogether, it never works and can only favor trafficking and make things even worse.
One good step, I agree, would be to ban a number of specific chemicals that are used in most industrial cigarettes, and known to cause various problems. That is not "banning tobacco", would do absolutely nothing to favor trafficking (no customer will want an illegal product just because it contains nasty chemicals that provide no benefit to them, not even getting them high.)
Heck, we could even ban cigarettes, but not tobacco (as in the old days before industrial cigarettes became mainstream.) That would drastically reduce the number of smokers while not being a complete ban.
Same for food indeed.
But even that is dubious - as you mentioned, taxes that are raised from it all are so huge that no state can really afford to do without them.
If it loses 10 billions a year, that's 10 billions that people will have to pay another way, and all of them, not just those who chose to smoke.
Health costs resulting from that are much lower, as some have pointed out, and even so, the effect on health costs would be seen only maybe a full generation later. Not that it's a good reason for not doing it, but just mentioning that for a generation, people will HAVE to pay a lot more in other taxes to compensate.