There are a bazillion types of plastic in the world. While silicone is suited to lubricate some, it is completely wrong for others. The lubricant has to bond to the surfaces and create a layer between them.
I took Tribology (the study of friction, wear, and lubrication) as a senior in college. Try the WD-40. Heykrop says it works, and the plastics in your controllers are probably similar if not the same. I don't think it will hurt anything. Use just a little, and take time to work it in.