Often those characteristics provide the product advantages you know and appreciate in wool clothing. The perfect example is the warmth created by the tiny packets of air which individual wool fibers trap naturally. But, another characteristic of wool yields the secret of why wool sweaters and clothing knitted from wool yarn can sometimes shrink. Two conditions are required for wool to shrink. Water and heat.
Every fiber has a love hate relationship with itself.
Even though wool wants to repel water around the fiber, at a certain point of getting wet, it reverses its process of repelling water to absorbing water. When this happens it brings water into it's core and holds it. But you have to be careful not to overdo the weave or the fabric will not be able to breath. Has to be a balance to get the best water shedding and breathability. In the microscopic view, that is under a microscope, the outside of the wool fibers look like they are made from overlapping shingles, like shingles on the roof of your house.