Why do they focus on food so much?

Dr. Heywood Floyd goes on a shuttle to the space station, and the meal is liquid nutrients through a straw. Then later on on the Moon it's sandwiches, then again later on it's Bowman and Poole eating what I can only describe as coloured paste as they watch the BBC12 interview featuring them and HAL. Then there's the final eating scene where Bowman, in the future or whatever, is eating when he smashes his wine glass and ponders it, which I found quite interesting.

I suppose that whatever our stage of development, we will always need food. That's what I take from those scenes.