The reason why everyone complains about lee sin is the reason everyone complains about Lucian and Renek. They are the safe picks. It's as simple as that. Cry all you want, but every single role has the "safe" champion that is going to be average at everything. The reason why everyone complains about Lee Sin, is there is NO comp that he's terrible at. People might say this is "bad" balance, but let's take a step back.
The issue is not champions being a "jack of all trades" in the specific role like Renek, Lucian, or Lee, the issue is they do everything decent to strong. It's enjoyable to play a safe champ like Lucian because he has everything, but with having everything he needs to do everything WEAKER than the other champs. People complain about Lee Sin being "op" and having everything, yet Elise has a similar kit and no one whines about her...
tl;dr: Lee Sin isn't op, he's just a safe pick because of his kit. Stop hating on champions with well rounded kits and hate on the fact that other champions aren't better balanced in their niches.