The real reason why the game is in the current state.

So, everyone is unhappy. Unhappy with the game in its current state, since bot lane decides everything, right? I think a lot of people exaggerate, but it's quite true. So, why is the game so snowbally, why is everyone finding it hard to have impact etc?

Well, we need to see the bigger picture, the real reason. That reason is that the game is simplified. What I mean by that?

Win conditions. Different metas have different win conditions. Right now, it's snowbally ADCs. Some seasons ago, it was splitpushing (Jax for example). Another time, it was pick assassin = win game. The thing is, right now, it's very easy to devise a plan to win and everyone knows it. Take bot tower, and snowball this to win, because the advantage is big. The difference with every other meta, where people still knew how to win, is that it's so easy and safe to execute. The hardest part is taking the first tower, after that, it all comes so naturally. You play a champion that, based on its range, is safe and can constantly AA towers, as opposed to a splitpusher. And that champion also has the safety of a support. Oh, and that champion also naturally itemizes in pure damage, which makes tower taking even faster and easier. It's easy to do and there's not much counterplay to it. Apart from having champions that can waveclear to defend (Sivir), there isn't really much you can do.

Now, let's take a step back to other metas. Snowballing wasn't as hard. No first tower gold for example. Also, imagine the Jax I mentioned trying to splitpush as the meta's win condition. What if a tank gets in his face? He can't really keep AAing the tower without taking damage. He also has to do this alone, which means no support from the team, making him vulnerable to ganks. Overall, the execution is much harder. Having your strong splitpush away from the team will probably set your 4-man team in a disadvantage, or they won't have much of a lead, seeing how the splitpusher has most of it. Therefore, while Jax can sidelane and take objectives, your team runs the risky of getting engaged on and dying, throwing away all the pressure. This can't happen now, or at least happen so easily. Seeing how the strongest person (ADC) is grouped with the team even from the early stages, the lead the ADC has is also present during teamfights, so the enemy team can't really exploit something, like a strong splitpusher missing.

TL;DR: It all comes down to how easy or how hard it is to execute each meta's win conditions, and right now, the execution is simple and safe and everyone knows how to do it. Back then, you either didn't know, because there wasn't as much information, or it was harder to execute.