Q- The hitbox isn't the issue, honestly this ability isn't the issue at all.
W- One of the things that needs a rework the most. A generic every 3rd hit passive heal that is identical to udyr's with the only difference being that can be swapped for jax's ultimate's passive.
E- A bit too generic, but is aight enough.
R- The extra range is cool, but it still just feels like an effortless mashup of other abilities, it doesnt inovate in any of it's regards (Burst of dmg scaling with ap that then empowers auto attacks - voli ult, temporary auto attack range buff on a melee champion - kayle e, attack speed buff - too many abilities to count)
Passive- Number 1 thing that needs a rework, it had potential as a way to incentivize to keep fighting beyond what seems reasonable and for making you feel like being in battle gave you fueled you, instead it usually either under-achieves and feels useless or it over-achieves and is cancerous to play against. Is very hard to balance/be fun to both aatrox players and ppl playin vs aatrox (rito chose to not have it be fun for the aatrox mains, since they are few)
Also, for such a recent champion, his passive feels very outdated. And the whole balls to the walls reckless fighting style was much better achieved by other champions such as olaf and kled.
Your idea for the passive changes makes no sense, aatrox wants people close to him, he survives off of attacking, if you knock everyone away after respawning then you just die again after while u try to catch up to the opponents. Not only that, but the 5 passive stacks make him feel much less resource management oriented and gives more room for just focusing on fighting, which is part of the reason he even had a health spent kind of scaling instead of mana, to let you focus more on fighting and going all out and less on whether you are gonna have enough mana to survive a potential gank.
Edit: The rework was a fail because the kit itself was a fail in many aspects. Imo Aatrox almost defines what is a champion that needs a full kit rework (think warwick or urgot)