Why is Kennen so weak?

I don't see any matchup where the Kennen doesn't lose. Even those he supposedly counters are really only if the Ken plays perfectly.

This champion has everything wrong with him. He has to run through his enemies to be able to damage them, yet he's squishy. He has long cooldowns combined with high energy costs and low energy recovery. He has extremely low base damage and very limited mobility. His stun requires set up and lasts half as long as other mages. He's limited to what items he can buy unless he wants to waste item value on mana. On top of all that, he pretty much requires flash for a good team fight initiation. Otherwise, he's easily CC'd before he can get into range to ult.

I don't even think a buff will do at this point. A full redesign is needed for this champion who is dead weight for his team to carry.