It seems like everyone's agreeing with you. However, I have a different view. Hear me out.
back then many things you did had inevitable consequences. Like walking to the Garen infected bushes. Unless you had flash, you just were bound to get silenced and spin-to-wined. Or walking near Veigar without enough HP/MR/allies to help - Veigar in late-game was designed to 1v1 most of other squishy champions. But he was unable to contest 2 champions at a time (unless extra fed).
Let's say that today, Garen hides in a bush and ambushes a jungler. Instead of killing them, a similar situation now forces them to go back. You may argue that this reduces the strategy required in the game, but I'd say that it reduces snowballing, which used to be a much bigger issue than it currently is. There's still reasons not to go into the bush with a Garen in it. It just isn't as punishing. Secondly, if you make a mistake, you have a chance to reduce the size of your mistake. It isn't just a flat out "You're dead or you're not dead". I would agree that Garen's not anywhere near the best place right now and needs looking at by Riot. The passive buff was a good start.
Take Veigar at the current moment. He's one of the most annoying champions to play against. Why? He has a very long AoE stun with long range. If he gets fed, the counter to this is to stay far away from it and start saving up for a banshee's veil or qss. What can you do if you are 1600 units away from him? Probably not much. What if he's a good one and can use flash + stun + QWR? He can kill you instantly. That not only harms how fun the game is (Feels like you have no options due to earlier mistakes), but also harms strategy. The strategy against him is very simple compared to dealing with a similar fed champion, even though he may be harder to deal with. Against a Veigar, you kill him before you send your ADC or APC anywhere near him. He can 1 shot one champion unless he's killed before the full-on fight starts. Against a Syndra, who has a relatively similar kit, it's a lot more complicated to deal with. She has a long range stun, but it hits only one person unless people are forced to go into a small space by Syndra's (Or they made a mistake). She has warm-up time before her ultimate does its full damage, so she needs to be prepared. This means that an adc doesn't always need to stay far away from here, even if she's fed. A 3 sphere ult won't do too much damage compared to veigar combo. Squishies can still take a good amount of damage from this, so they need to be careful, but not so cautious that they're out of options.
It's all the difference of binary outcomes versus complex outcomes.
Back then cooperation, tactics and positioning payed off. Now the best you can do is pick a champion with blink and short cooldowns and press the shit out of your Q, W, E and R.
I'm not sure exactly what you're talking about here. Cooperation, tactics and positioning pay off the same as ever. The difference is that now, instead of 1 big mistake deciding the outcome of battles, it's a bunch of littler ones.
I have also noticed that diving turrets is now much easier - another stupid thing you can do if you can fast-click.
Think of all the complex tactics that are involved in diving a turret. It definitely isn't just fast clicking, or even fast clicking at all! It's teamwork and cooperation and reacting to the enemy all at once. Not only this, but also the timing of it. You need to have very good map awareness to tower dive in the early game because a gank can easily mean a double or triple kill for the enemy team. It adds a lot of strategy because both teams need to be concerned of enemies' positions.
You just have to land and dodge skillshots, anything smart is considered troll and off-meta.
Most skillshots are more about the enemy being out of position than you being in the right position. An ADC is not going to be anywhere in the neighborhood of a morgana snare in most teamfights.
What's smart that's considered trolling?
When I played strategically with my friends, the enemy team called us trolls and said they will report us. Because strategy is now considered cheating!
People say stuff, and people said stuff back then too. This is partly nostalgia speaking.