Your Ask Riot: Janna Mid Post is Uninformed and Frustrating to Read
Janna was never a top pick mid lane. She has always been a niche pick, and she could not one shot waves early in the game at all. The statement you have that she could is incorrect (or as we call them now, an alternative truth).
Here's a video of Zekent, one of the ONLY AP Janna players at 4:20 clearing minions https://www.youtube.com/watch?v=cowgvXag-nw
As you can see, it's clear she cant just press Q and clear the wave. She needs a fair amount of AP to do that, even then. Most mid laners can still do it better than she could, including Ahri and Viktor.
As someone who found AP Janna really fun and engaging, I find it sad you think she was just a wave clear bot, when you can actually go through and watch videos proving the opposite is true. I'd argue current tank shield bot Janna is a lot more fucking boring than what AP Janna used to be. But I guess that's none of my business that you force her to build the same 3 god damn shield items in the same position every game. Who cares about diversity?
And no, her ability to go mid didn't even get removed because of her waveclear nerf (though that obviously did impact it) - it's because you literally gutted the AP ratios on every single part of her kit.