Honestly...... While I don't play as much as I used to, I find the game more fun now.
I have played in every season since S2 and I honestly think the game has improved. Itemization has become smoother and roles have become more defined.
S2 was trash..... The jungle role was goofy as fuck and had very few viable champs.
S3 was better but still pretty wonky. The only viable champs in the jungle, for the most part, were AD and you were bottlenecked into 1 build for all of them.
S4 was nuts. It had so much shit changed that the jungle was a radically different place with Smite buffs and a shit load of smite items. It was a massive change, but there were plenty of bad changes that came with it. Devourer was so completely busted that it wasn't even funny. You would jerk off in your jungle for 30 min come out and 1v9. The XP was so insane that ganking was pointless because of the aforementioned 1v9 you would be level 18 when everyone else was level 14.
If you think S5 was any better, oh boy. You know what jungle diversity means? It means picking between vi and jarvan, and hell what are we even talking about they may as well been the same champ. "oh you wanted more jungle diversity?" We will just remove 5 AD off of Warrior to bring tanks more into line..... 5AD!!!
Honestly, S9 is one of the most balanced and fun seasons the game has ever been in. Tanks are viable, Assassins are viable, Bruisers are viable, Mages are viable, Marksmen are viable, Hell even goofy shit in the bot lane like Yuumi Garen Actually is viable and played on the Pro stage. The game has never been in a better place and the people who think the game was better before have rose-tinted glasses on.
Now sure there are elements that I would like to see brought back, but a full rollback doesn't address all the silly shit that was so completely and utterly unbalanced in the game that made it not fun.