One good reason is that the plug you are using is standard copper spark plugs.Autolite is platinum.
With platinum pallet loaded spark plug,you can get better spark, more focused ignition,the result of which is smooth and better acceleration.improved fuel consumption.Also better life than copper plug.
The Autolite AP63 available is of standard length.If your cars manual recommend only long tip spark plugs,then stick to them.Otherwise you can check Autolite.