I'm a big fan of hydration, too. Since our bodies are mostly water, hydration is essential for us to function properly. When we were young, we could compensate with our youthful invincibility, but as we age, every little bit helps.
I have low blood pressure, so hydration is important just to keep the volume up. But absorption of nutrients, distribution of medications, you name it - it all requires water. I literally carry a stainless steel bottle of water with me everywhere I go. Of course, what goes in must come out, but it's worth it in the long run.