Wilson makes very good products so if you want a full length guide rod in your gun you can buy with confidence. Do you need one? No. The 1911 pistol was designed without a full length rod and has worked just fine that way for over a hundred years.
However, in IPSC we use full length rods pretty much exclusively in our competition guns. Admittedly, many of the guys who use them have no idea what purpose they serve because they don't get too deeply into the nitty-gritty of race gun tuning. They just buy the gun and go shoot it. The ones who are always tinkering though, looking for that extra little competitive edge, know that they can be used to help adjust balance of the gun to preference. Different materials and designs like steel, polymer, tungsten, as well as aluminum, mercury filled, Recoil Masters, etc., all yield slightly different results. Putting the extra weight of a steel or tungsten guide rod up front in a gun adds some recoil dampening effect but also adds recoil dwell (added inertia and momentum), which is something that can be tuned to personal taste by playing with materials. They also help smooth out the cycle somewhat, though most shooters wouldn't be able to tell the difference...especially on a standard-sprung .45. They are a must-have for most compensated guns due to take-down requirements.