Why Lulu's passive is siphoning out her power from the rest of her kit
Her passive is either the number one or number two reason she has shitty base stats and bad damage on her Q and E (other potential rival is that her kit encourages high-counterplay playstyle despite being non-ideal in terms of outcome). Wanna know why?
Her passive is the second hardest hitting thing in the game at lvl 17. It hits harder than Nunu's fully changed ultimate until 200 AP. She deals more damage than hitting all 3 of Xerath's ults. She deals more single target damage than a full channeled Kat until 700 AP. The only thing that can out damage her passive is Fiddlestick's ultimate.
And all of those ultimates have some form of charge, miss, or ability to be walked out of. Pix does not have nearly as much leeway. You are going to get hit late game if Lulu is in range.
Is it hard to reach 2.0 AS? No, that's why we have Jinx, Jax, Irelia, Kalista and a bunch of other people with tons of AS scaling. Is it hard to keep uptime on a target for 6 seconds? It was in the beginning when fights were decided in 3 seconds. Now? Proper training in attack move can easily allow the user to get 12 attacks off in 6 seconds. I say this is an extreme because it kind of is. You're not going to get that damage in Bronze because people don't have the mechanics, but in Diamond? The ability to give all that damage to Kalista? She doesn't even care who she hits as an ADC; she just wants to hit the highest priority target that in her safest range. She doesn't care and as the meta has changed into burning down tanks instead of straight diving, this is absolutely perfect.
And when she's in solo lane, she just E's someone, squishy or tank, and does the same thing.
The really funny thing is that her innate is pretty much useless at lvl 1. See, there's a bug in it that all flat block is subtracted from her autoattack and then also from her passive. So a Leona with +4 block effectively has +8 block, and the ADC effectively has +6 block. Combined with her low AD, this makes her harass nonexistent until lvl 3. And then you get to lvl 17 where her passive just melts people when used properly.
Would you build MR vs Kat? Of course you would. With 200 MR would you just stand in her ult with impunity? Of course you wouldn't because that thing hits like a truck. So now why would Riot let the exact same thing happen except now it's targeted and you can't simply walk out of it? By itself Pix has counterplay. The bolts are blocked by units and she has low MS. Except E makes it virtually impossible to miss, W/Q makes it virtually impossible to escape, and she can simply reposition Pix on her ally to get around any obstruction.
Lulu is over 3 years old and has proven time and again that when she's good she's good. When she was good at supporting in early Season 3? She kicked out Taric as the best burst support and had the most favorable matchups until she was nerfed, and even then held her own until Nami was released and then followed by Thresh who had more appreciable utility and allin. When she was really good mid? She was oppressive. When she was really good top? She could shove and play safe because the jungler didn't want to go to the Lonely Island. Much of that is blamed on Q and E. Q has waveclear, is relatively fast, and hits fairly hard. E is instant and has decent range while also giving vision and allowing easier Qs. But many fail to realize that a huge portion of her damage still comes from her passive at lvl 7+. Everything in her kit allows her to ignore the downtime counterplay built into her innate.
Time for an example. Let's say Lulu is level 7 with a total of 120 AP. Now, reword the E to say the following because this is essentially what using E on an enemy does: >When used on an enemy, Lulu loses her passive and instead gains attack damage equal to the damage her passive would deal for 4 seconds.
Ok, so at lvl 7 she gains 63 AD for 4 seconds. Not even Janna's E is that powerful. And that's with minions around. She doesn't need to do the above if there's no obstruction. This is why Lulu can't have nice things. This is why Lulu has her Q and E damage nerfed so often, and now that there are plenty of viable targets to abuse the damage on and plenty of viable allies to reach that ever so amazing 1260+1.8AP magic damage, it's going to be the reason why her QWE are going to be shot again.