Water is NOT preferred by people and primates.
Look at all the non water drinks being sold commercially... that is the big bad clue that people do not prefer pure water.
GS I think its all about where you live. I can tell you were I grew up, in the summer time its 100 degrees and 3 percent humidity, Humans there prefer waters, LOT of water. the natives gravitated to the natural springs and that is why my town is where it is. You sweat in that climate and its like the water is sucked right out of you. Here in Idaho its very humid even when its 100 degrees(like yesterday, aack!) and so you sweat but it doesn't evaporate so its not really that efficient of a system as it is in more arid places. I am sure you are more used to being in humid climes, GS, and do not sweat as profusely as I do, because my body is not accustomed to humidity. This is likely why you probably require way less water then I do.
I think there is so much going on besides preference for water or not.
Think about how in summer we are given more foods with high sugars, like fruits and berries. It is known that with higher blood glucose we are likely to hold on to much more water in our bodies, so it is a natural part of our bodies keeping us hydrated when it is hot. That's why things like melons are so super hydrating, simple sugars, minerals and a lot of water.
So all of these things, climate, humidity, ethnicity, seasonality, food source, all of those things come into play.