Why developers killing old-school champions and playstyle ?
Arguably seasons 3 - 5 were the best. Mages were mages and were playable, adc were adc and were playable. There were also a small number of assassins who kept meta at bay.
Everything started to go downhill when RIOT decided to shift their attention primarily to E-Sports. More speed, more action and interaction made big number of old-school champs and meta unplayable, champs and meta which made this game so popular in the first place.
Same happen with StarCraft. Original SC:BW game was so fun for casuals that it naturally became E-Sports. SC2 was primarily made for E-Sports in mind and therefore it never reached expectations despite it's early hype. Unfortunately, LOL blinded by its early success now walks the same path. Players are leaving this game. In fact, Internet traffic for LOL went down to 30% of what it was back in 2015. LOL still speaks about big number of "unique players", while in fact everybody have at least 2 - 3 alternative accounts and if you tried to level new account you noticed that most of them are smurfs too. There is a reason why LOL introduced new MISSION: "Teach a Friend" - because there aren't enough new players to play this game.