I understand what you mean. It can't be neglected though that obesity actually changes your brain chemistry (I was a neuroscience major and read a lot about this).
It's also important to note that behavior is motivated by reward. Staying hydrated is important and it is so much easier when that beverage is sweetened. While tasteless water may not be a big deal, creating a sugar free lemonade I'm sure would definitely increase how much water you drank each day.