After she got her update she was really weak still. So, they buffed her a tad. Still too weak so they buffed her a tad more. The final tweak that decreased her rapid fire and explosive charge cooldowns as she attacked while they were active really put her in a healthy spot. She felt really good and rewarding to use. She was not considered OP and hardly anyone used her.
Fast forward a bit and boom, high level players are finally realizing her potential and where she fits in a team. This was a shift in the meta, happens all the time with a bunch of different champions. She does well enough in the lcs to get an article written about her and it is thrown right on the front page for millions of gamers to see. She gets a huge spotlight shown on her and her play percentage skyrockets.
This is where nerf "insert champion here" topics start popping up. Just like this thread. Would you have cared about her or her balance before she was a part of the meta? Or is it just because you keep playing against her and are annoyed by it.
I guess what I am trying to say is, just because a champion becomes part of the meta, it doesn't mean that champion is OP. Yes, in some cases a champion being OP is the only reason it is part of the meta, but I do not believe this to be true with Trist.
If you want to know some real reasons why Trist is popular now (apart from her fame in lcs) here are some:
*the current meta runs upon late game hyper carries> Trist is one of them
*tanks and bruisers are apart of the meta> Trist has a nice knockback and an escape perfect to keep bruisers away
*high level league and the lcs rely heavily on objective trading> trist is good at taking towers quickly so you can destroy the enemy tower faster than the enemy can destroy yours, thus resulting in quicker rotations
Before posting asking for nerfs, think about WHY a champion is so popular. Read patch notes and observe what is happening to league that would make a champion stand out even without it's kit and stats being OP.
Trist is a perfect example of how champions become popular (and OP in some peoples minds) without actually being adjusted themselves for some time.