Rengar Disappointment

I was a player until season 2, I recently rejoined the community after, about 6 years later right? I quit because of the Rengar nerf but came back because the game can still be fun. I'm disappointed that he is even weaker (or sure seems that way) than when I left. He was my favorite character for his visuals and his kit was so fun to play! I never see a Rengar, ever. I'm confused as to why he was put second to Kha'Zix, as Kha'Zix is still really strong. Hopefully someone can maybe shed some light onto why my most liked champion was buried before his time, and maybe, just maybe, you can at least make him viable to play against the stronger champions.