Community response to Garen reworks in a nutshell:

Perseverance: Community response - "It's a built in Warmogs!"

The exact same passive he had before

Decisive Strike: Community response - "The silence is too long and he goes too fast"

Both the speed and the silence were nerfed significantly during the rework

Courage: Community response - "He takes no damage!"

He took even less damage before, plus he had a bonus %35 tenacity with it, and %20 to all bonus armor and magic resist on your bonus armor/magic resist

Judgement: Community response - "Actually, we're pretty down with this ability"

It was virtually unchanged, save the fact that you spin faster as you level up

Demacian Justice: Community response - "Villainy does too much damage and %HP true damage is dumb!"

The purpose of Garen's rework was to give him the unique role as an "Anti-Carry", and to Garen not care if you're a 984/0/42 Vayne/Jinx/Any ADC at full build, he WILL kill you, which at max, He'll deal an aditional %10 max HP true damage, which for a carry, (Assuming that you're actually pretty tanky for an ADC, so we'll say, what, 3000 HP?) will deal a bonus... 300 true damage, that's a sizable chunk, but not totally devastating.

My point is, that every argument for Garen being OP is less of a problem now than it was before the rework. According to your arguments, Pre-rework Garen was like pre rework Kassidin. The reality is the exact opposite, Garen was a laughable pick for noobs to learn the game that would never see top tier play (And even still, Garen doesn't see top tier play)