Most people don't. In fact, water is one of the most important nutrients we can consume! It's so easy for me to drink copious amounts of Diet Coke and forget all about water.
Our bodies are about 70% water. We can survive for quite some time without food, but only a day or so without water. Water lubricates our joints, keeps our skin soft and youthful, and carries waste products out of our bodies. Like, you know, extra fat.
Some people dislike drinking water because they don't want the "water weight." If you haven't been drinking enough water, some annoying side effects will develop, like the need to pee every few minutes and some water retention or bloat. The great thing, though, is that as your body realizes it's finally getting - and staying - hydrated, those side effects go away.
If you like coffee, tea, or sodas, water becomes more important. Caffeine is a diuretic, so the water you lose to drinking caffeinated drinks must be replaced. If you enjoy alcoholic beverages, you can avoid a hangover by drinking plenty of water with them (as well as after your binge).
So sip on water throughout the day. If you really hate your water plain, float some lemon slices in it.
Your body will thank you.