One of the aspects that I really thinks sets Xsyon apart from other mmos is the level of realism involved. Some people enjoy it, and others don't. However, I think that if you go there, you should make sure to fully commit to it.
One of my pet peeves in games is seeing someone who is fully clothed/geared swimming across a river or lake like it is nothing out of the ordinary. Realistically, bodies of water form natural barriers that are not so easily passed. They present a challenge. You might slip into some swift running water and get swept away and drown. You might decide to build a small bridge across to encourage trade. You might want to have canoes or rafts to utilize the natural transportation power of a river.
Much of this excitement and challenge is lost when you allow people to just jump in to a freezing lake or dangerous river, casually swim across or through it, and come out the other side as if they had strolled down the lane on a sunny day.
Since Xsyon chooses to make our challenges reflect the real world, I'd like to see something in the game mechanics to discourage people from treating water so nonchalantly. Maybe our characters could become uncomfortable and stay that way until we find a shelter to rest in with a fire. This could represent their ability to dry up and get rid of that nasty cold.
Of course, many people would choose to circumvent water and that would make sense. It would fit with the world that is presented to us.