The Palm protectors protect you from vibration and heat, which causes blisters. Avoiding blisters allows you to ride longer, ride harder and ride safer. Some people claim they don't need the protection because of thick calluses, yet blisters can actually develop under calluses and when those break open, they are more prone to infection.
The Risk Racing Palm Protectors are so thin they slip right under your gloves. You don't even know their on. The vibration reduction can also improve arm pump.