He has damage early and mid game, but is in the same boat with Pantheon when late game comes.
He DOES die quickly in team fights if you focus him down. He isn't as squishy as an ADC, obviously, but he is no tank.
The current most common Lee build is
.
Only two of those items are full on defensive, and one of them not only has a cooldown but also sets him up to get burst down again when it revives him.
He doesn't have that much CC. His E doesn't really count, since that slow sucks ass. Besides that, he has one cc spell. Yes, it's a good one (if they position in a way that allows you to use it well), but he is hardly Nautilus.
He DOES have problems in sustained fights. Most of Lee's damage is burst. His sustained damage isn't the worst out there, but it's pretty far down there as far as fighters go. Lee doesn't GET a shield in most fights, since the shield just doesn't happen if he uses W to ward hop (which he most likely will). 30% lifesteal and spell vamp is significant, but since his sustained damage is so mediocre, he doesn't benefit too much from it.
Have you ever played an energy champion? It doesn't seem like you have, if you think that he can just "Hurr Durr no cost spells yayyy!". No.
Energy champions don't have to manage their resources much outside of fights (laning, farming, etc) but in exchange they have it MUCH harder when it comes to in combat resource management. In the case of Lee Sin, each spell costs 15-25% of his resource pool. If he spams, he runs OOE and dies. His passive helps, but not so much that he can just mindlessly face roll.
I'll give you mobility. He is certainly fast.
Seriously, you didn't even TRY to think of weaknesses. You literally just listed his strengths (and misrepresented them quite a bit at that).
w/e
Glad to see the anti Lee circlejerk is alive and well