We have seen so much Lee Sin these past years that we have gotten fantastic at fighting him

I think this is why his win rate is relatively low compared to how strong he is in general. Look at his play rate over the years and it is consistently sky high. I feel like I play against a Lee Sin almost every 2-4 games through the years and I know his tricks so well that I am incredibly comfortable dealing with him, despite the fact his kit is more overloaded than most champs and I would argue he is stronger than anybody in the jungle outside of Graves (shaco and ivern I feel are just taking advantage of the ridiculously long clear times everybody else has to deal with.) He probably doesn't need nerfs, but not because he isn't significantly stronger than other champs, but because we are all forced to deal with him so often that it's reduced his effectiveness.