Sett's kit just feels really bad to play against

Why does Sett passive give him a built in auto reset on top of a Garen passive? I feel like there's really no reason why he needs to have the regen portion. His passive is already incredible. It allows him to get off tons of auto attacks in a short time. So, he not only gets a 300+ strength shield at level 1 that allows him to automatically win trades, but if you manage to win the trade he just heals up for free. I just feel like it is awkwardly tacked on to his kit and makes him way harder to fight than he needs to be. It's a classic example of Riot handing out free shit. Max health damage on Q and ult, auto attack reset for Q, and auto attack reset on passive. Let's not forget that he is literally rewarded for taking damage! It's one thing to have a stronger heal or something for low HP, but the better you perform against a Sett the more he is rewarded. There are so many times where I will be winning a trade against a Sett and he just automatically wins by pressing W. This isn't even assuming he hits the true damage. He just wins because he gets the strongest shield in the entire game. On top of that, it allows him to tower dive WAY too easily. I have done it myself where you can just beat the hell out of someone under tower, press W, and you are perfectly fine because you get a massive shield. In other words, Sett has damn near any counterplay. You can't trade with him because of passive and W, and you can't outscale him, because he scales incredibly well.