Let's see here:
She is only picked because she's easy to play and is easy to win with and nothing more. She certainly isn't picked because she's fun to play as, that's for damned sure.
The starting skill level on her is pretty low, but the skill cap is pretty high. Knowing the right time to interrupt abilities with your tornado and when to ult at the best time take lots of practice. Personally, I don't find her boring to play at all. She has great mobility and you can impact multiple lanes.
The definition of a non-interaction lane Incredibly boring to play as and against
Someone must be a skill-shot master. I don't know how you find having to position that tornado properly, ult in appropriate situations(also know how to ult i.e Heal or Disrupt.) and apply that shield constantly "non-interactive." I don't know about against, but I find it fun to play as Janna. There is nothing better than landing that tornado, shielding an ally from death or even a turret and getting in a good ult to disrupt the enemy team or just heal my allies. Also she's the original mobility champ of League, seriously 490+ MS is really fun to play with.
I got forecast Janna and i enjoy playing her. Also the fact that a champion is easy doesn't mean he needs a rework, not all the champs need to have a high skill cap to play, as a reminder there are newcomers every day to league and still people stuck in bronze V. Also according to your post you are saying she is a freelo champ. Which literally made me laugh, I never thought a day will come and people will complain about JANNA being overpowered. she is a normal backline support who will get killed in two seconds if they dont have ult.
There's something really funny about these types of posts.
"X champ is so easy to play and broken" The guy doesn't even play the said character.
If Janna was easy to play and can climb ranks easily, why don't you play her yourself ? You said it yourself, you can just main Janna instead of buying an elo boost.
Janna is hard to play because of X main reasons :
And there's more, but these are the 3 reasons why I don't play Janna anymore.
I find Janna to be Toxic-Cancer who needs a god-damn nerf/gutting
