For me, food and drink means:
a) demands on my carrying capacity
b) demands on my gold reserves
c) exposure to famish and the druid commune that causes thirst
d) limited ability to eat
e) disincentive to use bloodlust
f) having to carry a way to replenish water

And then there are various alternatives:
a) gambling for pouch of nourishment
b) trading/killing for the same
c) likewise for water
d) useful items that prevent hunger / thirst
e) useful items that enable eating unlimited amounts

If you're a shaman (in particular) or a druid, these things are quite useful. For anyone else, there are significant differences between having to buy food and not having to buy food.