less sure about the increased sensory inputs and their role in helping to improve comfort.
We have a sense called proprioception, or position sense, knowing where you body is in space, without having to look at the body part. Think of when you are walking, you do not have to look at your feet to know how to walk, or where to put your foot each step.
When ACL, PCL and other nerves are cut, the nerves that conduct position sense are cut too. With less information your muscles do not work as well at modulating the contraction, stronger weaker, or firing at the right time, and so on. So your knee may be more unstable, because those muscles do not fire like they should just when you need the support.
The feed back system is impaired, which results in your motor control being impaired.
When you put the knee sleeve on you increase the sensory input, via compression, the sleeve moving on your knee, etc. Now our brain has more information, and can send more accurate signals to your muscles so they fire like they should, controlling your leg and knee, increasing stability, and you feel better. Another example, if your glasses are covered with grease, you can still see, but would you drive safely? NO, because you do not have all the information (feed back) you need to control the car accurately. This is what happens to your muscles when the nerves are cut for proprioception. Less information, less motor control.
I worked with an individual who had a stroke a long time ago, his proprioception was absent, he had full motor control, only when he could see his leg or arm. Otherwise his hand and arm would writhe through space, his brain was trying to figure out where in the world his hand or arm was. He often got it caught in the spokes of his wheel chair (not good) and other places it did not belong. When he could see it, his hand and arm had normal movement. We have numerous types of sensory receptors, pressure, hot, cold, proprioception, light touch, deep pressure, some keep track of muscle length, speed of change in muscle length, etc. These receptors are located throughout the body.
Hope that helps, our neurological system is very elegant, and complex, reaching every corner of our body, and monitoring every function.