While walking by a box of cat food the other day my mind went down a weird thought process that ended with the above question. My cat lived for 19 years and during that she ate the same cat food day in day out with the only addition to her diet being the odd mouse/bird/insect she would hunt down and devour.
If they can make a food that has all the nutrition needed to keep an animal alive for 19 years why isn't there a human equivalent? Are human bodies more complex and require more to live then animals? Obviously it would suck eating the same thing all the time, but I'm sure they could flavour and texture the stuff differently for variety and just because you have it doesn't mean you can sometimes eat something else when you just need a change of pace.