Stopping the ladder from skidding
Generally, the number one fear when it comes to climbing a ladder is vertigo: looking down and getting that feeling in your stomach can be very unpleasing. However, that fear is irrational. Fearing that the ladder could slip is entirely rational.
Two smooth surfaces enable sliding and are likely to make us feel insecure when we are up high. If one of those surfaces is ruffled or ragged, motion is more likely to be stopped. A foam handle can help with that.