Turrets do survive more than two hits. They die quickly enough that outmaneuvering an opponent can take a turret but not so easily that you can kill a well guarded one. Towers do more damage for each consecutive shot, that way diving is possible if you can stay for a short time but not over a period. Poppy can definitely not tank a tower for 2 minutes. If you are having issues being dove then dance around the turret a bit and let the turret do the work. You are probably fighting back expecting the damage of another player immediately when that isn't what you are going to get, nor what you should get.
I kind of agree on the damage is too high, but that mainly stems from the issue that if a tank could take damage from 5 people reasonably well then there is no way a single person could outplay them to win, especially if they do something relevant besides taking damage.
True balance is completely unachievable and would lead to very, very stale gameplay. What we have is asymmetric balance, which means that it is completely ok for a character to have statistics above other characters as long as they have counters that can defeat them. This leads to a situation where a lot of people play champion A until they realize that champion B beats that character, who is countered by champion C. Then it comes full circle as champion A counters champion C. As league has many more characters than that it is more complex but that is the idea. I have not played against Camille much but I would put money down that she is countered by somebody.
Ranked is perceived as poor because you have people on your team who lose to the opponent occasionally, generally due to him being slightly worse than the opponent, and then gets harassed for feeding. There are games where there are true intentional feeders and trolls but they are relatively uncommon in comparison, and the situation I described is completely avoidable if you just help the person. If you try to help him and fail then you are probably worse than the opponent as well and deserve the loss.
The general idea of adc's is that your team pumps gold into them so they can buy a bunch of expensive items and use them to tear a hole in the opponent's team through sustained damage. Due to this, most of them do not build defensive items, which means if you outplay them you can tear through them just as easily. I don't really see a problem with them to be honest.
The population of this game is rising and is still the most played game in the world. I don't think it is going anywhere soon, but I have been wrong before. It is just that the numbers do not support your statement.