Why are football shoulder pads are necessary?

Generally, football shoulder pads have been made the same way since 1900. Material is stitched, laced and molded to cover essentially the same parts of the body traditionally protected by shoulder pads. As the Sports Illustrated Evolution of Protection in Sports website points out, the big difference is not in the manufacturing but in the materials. Football pads became regular equipment early in the 20th century. In the early 21st century, shoulder pads retain their basic function: to protect you between the shoulders and the lower chest; however, the materials to make shoulder pads -- once so rudimentary -- have improved.
Early Shoulder Pad Materials
When shoulder pads became protective items in the early 20th century, they were made from canvas or leather with moleskin padding underneath. The padding only was one-eighth of an inch thick and provided little protection. By 1935, sports equipment companies like Spalding and Rawlings made shoulder pads of canvas and leather that were cantilevered. Pads of canvas -- or leather -- held by straps rose high above the shoulders to better absorb hits. Later, underarm straps and extended plates were added to better protect the chest area.
Modern Shoulder Pad Materials
Major innovations in shoulder pads came in the latter part of the 20th century, when canvas and leather material gave way to hard plastic shells and foam padding that reduced weight while making the equipment stronger. Breastplates were lengthened to guard more of the chest and ribs. Shoulder pads became a specialized piece of equipment with certain features matched to specific football positions.
21st Century
The latest shoulder pads, as of publication date, are lightweight, less restrictive and durable. In 2003, shoulder pad construction added pads developed from dry polymer material developed by NASA. The 1/4-inch polymer doesn't compress as foam does, so players can absorb multiple hits without as much impact. Cooling systems are a part of shoulder pads. Utilizing multiple foam layers to draw moisture away from your body, pads are more breathable, which lowers your core temperature to reduce the risk of heat stroke. Some companies are experimenting with a form of air conditioning for shoulder pads.
Specialization
Shoulder pads are made for every position, although some are geared for more than just one position. For example, shoulder pads for quarterbacks also work well for wide receivers, since both skilled positions need protection without sacrificing mobility. Features on these pads include swim-cut arches -- which give more range of motion -- with a compact shoulder-protection system for more mobility. Other positions have different needs. The latest features for offensive linemen include a longer area of protection in front and back for taller linemen, material that prevents defensive players from grabbing and holding onto your pads as easily, and a double secure fit with both elastic and belts. Shoulder pads for linebackers, which work equally well for fullbacks, are designed to cradle the AC joint in your shoulder from the repeated hits you give and take at these positions. In addition, the pads use Biothane belts and snaps to dissipate energy at impact. They also have a liner that promotes air circulation for increased comfort.