I think food & water in meaning of items, would be pointless, and lead only to Fonline the sims.
But idea of food & water in meaning of fuel, which can be filled up only in bars in cities and bases, sounds nice to me. It brings more people to towns, and that means more RP.
For example: Every 4 hours i have to go to bar and eat meal, for 10caps (if i have nothing theres a brahmin pen, so 1 shit = 10caps=1 meal:P). If im logged out, cooldown isnt counting. If im out of 'fuel' i have -1 AP and only 3/4 available HP. So can still play fonline, but it pushes me to visit nearest city.