Gate contact is part of ski racing, and armor is what makes it sustainable. A slalom racer takes hundreds of hits a day on shins, forearms and hands; a speed racer needs back and torso protection for a fall at speed rather than for gates.
What you need depends on the event. Slalom: shin guards, arm guards, a chin guard on the helmet, and gloves with armored backs. GS and speed: back protection and a padded top under the suit, since gates are cleared with the body rather than punched aside.
Fit is the whole point. A shin guard that rotates around the leg or sits too low protects nothing and gets in the way of the boot cuff.