Imagine for one moment that you are completely without tension. You'd be on the floor, swallowed up by the Earth's gravity. You wouldn't be able to move one muscle in your entire body. That also would mean you wouldn't be able to feed yourself, hang out with friends unless they came to you, or play guitar.
Now imagine the opposite. Imagine that you have as much tension as the Golden Gate bridge in San Franscisco. You also would not be able to move one muscle in your body. You also wouldn't be able to feed yourself, hang out with friends unless they came to you, or play guitar, either.
Any which way you put it, it sucks.
The most common way of approaching the tension problem in guitar is to polarize it: Find the extreme opposite, and see if it's better. But, there really isn't anything better about one way or another. One way leads us to feeling like a wet noodle, the other like a stone.
It's one of those "duh" moments, but having a good balance of both tension where we need it, and eliminating tension where we don't, is key. It might do us good not to polarize in an effort to compensate. Instead, it may do us well to give a slight nudge to the right conclusion.
A person who is on the too-much-tension side of the spectrum (and most people are like this), might do well to focus on the tension that collects in the mouth. A person who is on the too-little-tension side of the spectrum might do well playing an easier playing guitar, using smaller gauge strings, and building up strength slowly.
The take home message? A balance of tension can be found quite gracefully, and effortlessly. Perhaps it takes exploring the absolute opposites in order to find that balance (I have most certainly done my share). Once found, we don't regret the path.