Why are towers so underpowered?

I started playing back in season 3, and so far, when ever its come to towers, they cant do anything useful anymore. they don't do enough damage to make people have to decide if diving would be worth it, they lack the range to keep off harass from the front when your directly next to the towers, and they don't have enough health to be worth trying to save for the most part.

I've played so many games where people have been able to walk in with slow champions like and fight people who are at full health under their own turrets and walk away only losing 200-300 health from the turret it self. or seeing adcs be able to attack people directly next to their tower with out the tower attacking them or even selecting them as a target. and the part that irritates me the most about the turret's current state is that its health is so abysmal that even if people fight under their tower during the team fight, they still have a very high chance of losing their tower anyways. I have been on both the receiving and delivering end of all of these points and honestly I've just been disappointed and upset. I always thought towers were supposed to be strong defensive structures that protect their respective team well enough it requires a team fight to take one.

honestly i feel that in this current state, one of the most important structures in league is so unable to do its job that it makes the game not fun to play. that's my main concern with the towers, with them seeming so weak, it ruins some of the fun of the game. I doubt riot really cares to much anyways since i'm not some one from lcs or even a high elo, but honestly i feel like this is one of the reasons that people are not enjoying league as much as a whole, since when ever some people complain some thing is to strong they eventually nerf it just ruins the original thing or concept. i really wish riot would pay more attention to the community and listen to more peoples feed back so they fix their mistakes.

anyways, that's just my opinion on the turrets as of 6.9 and on riot's balancing team as a whole