http://www.ongamers.com/articles/full-champion-pick-ban-stats-for-worlds/1100-2264/
heres some stats about worlds i think you're memory is a little foggy, he was rocking a 39% ban rate, a 59% pick rate, and a 56% win rate. the nd highest winrate being kha'zix who was picked more admittedly (because he was banned less and was the best pick when lee was banned)
lee sin being a jack of all trades champion is a BAD thing, it doesn't matter if nautilus is a better tank with more control, you'll never see him in the jungle while lee sin gets to have so much all around power with no true weakness. the thing is, lee sin does everything and does them all relatively well, he wouldn't be picked so much if he didn't, you know why i know this? elise does everything too but she certainly doesn't do everything well, so she's literally a master of nothing. maybe if lee had elise's numbers he wouldn't have such a death grip on the jungle options in pro play, but unfortunately he would be trash tier which i don't want.
i think a lot players have this bad mentality when coming to balance. "i hate playing against this champion so i want to be nerfed until no one will play it" which is really shitty, i think we should think more along the lines "i hate playing against this champion so i want them to change the obnoxious frustration points" lee sin's mobility is cool, his double spell combo's are cool, his inSec plays are cool, whats not cool is him 1v1ing me with a sight stone and 2 long swords while i have a warrior enchant, whats not cool is his absurd scaling on his ultimate on top of a high base damage.