The main thing that towers need is a mechanic that protects champs in their range, some small regnerateing shield, def stats buff, or some flat damage reduction.
Just something that makes it harder for opponents to harras or even all in you underneath the tower.
Increasing the tower damage wouldn't be sufficient for that, as many issues come from high ranged champs harrasing you underneath your tower without ever getting aggro, or some melees comboing you and only takeing one shot.
the other big issue is how easy it is for many sololane+jungle combos to towerdive once they get a bit ahead, and unless you really overtune towers, more damage would not do much as most of the time the victim just dies to fast while usually one of the both can easily drop agrro after the kill.
Some buffs to their KI would be nice aswell. If for example fizz drops agro with his E and there are minions nearby, the tower will switch on them till the next time some deals damage to a champion, allowing to corner your opponent while waiting for CDs while also reseting the tower rampup. If towers instead would stay alert and auto focus champs for some sec after dropping aggro it would make dives much harder to execute already.
Those are mostly things that are needed for the early.
later on it should be well possible to dive and tanks should be able to tank it easily, it's supposed to be maybe worth a 6man in a lategame fight and not more.
however, they need to be more resilent later on, it's absurd how they can fall in mere seconds come to lategame.
Same with other objectives aswell, Dragons and Baron dropp awfully fast so you have to guard them 24/7, even 10 sec with no vision can allow an opposing team to rush it later on.
though both those things are mostly symptomes of the overall damage creep...