For one, Lucian's sitting at a 50.5% winrate.
And the reason people don't complain about him is simply because while he's good, he's not dominating. He's a safe and good pick, that's all there is to him. Good sustained damage, good lane burst, good mobility. However he pays all of this for extremely range, no CC and no self peel.
Second of all, most people agree blue ez is really strong atm. But honestly nothing at all changed about him from the old blue ez. He does the exact same amount of damage and he was never buffed.
Vayne was a bullshit champion because she had no weaknesses. She had god tier mobility and the best kind of steatlh (no cooldown and instant), god tier damage, and good self peel, which basically completely negated her short range. And especially in a meta of tanks where she could basically sit in one place and just three shot everything, that was bullshit. The only thing that vayne was not a god at was lane phase, and even then her "weak" lane phase ended by the time she got a vamp scepter.
Corki on the other hand is absolute bullshit.