Why is Graves the ONLY champion with FREE natural scaling to his basic attacks?

Look at Graves' passive. At level one he does 70% AD on the first pellet plus 23% for every other pellet, up to 140% if he hits with all 4 on the same target (which isn't too hard). At level 18 it's 100% AD on the first and 33% on the rest, up to 200% if all hit, essentially being a FREE crit as long as he is close. But with the standard graves build of being close to an enemy isn't an issue, as well as his FREE 10-30 armor and mr (based on E rank) each time he dashes, up to 40-120 armor and mr. Plus, if he crits, it's then 6 pellets that do 40% bonus damage each. So, at level one if he crits (somehow) it's 98% for first pellet and about 33% for each other one, adding up to a potential 261.33% AD for a basic attack. And if he's level 18, it's 140% for the first pellet and 46.6% for each other pellet, up to a potential 373.3% AD. This isn't calculated with infinity edge bonus since I rarely ever see a Graves build IE. I'm just tired of playing against this guy, see him build bruiser, then deal the most damage out of everyone else in the game even if he feeds at the start, while being extremely durable due to lifesteal and his 120 free armor and mr. But I feel like the durability wouldn't be as bad if he wasn't the only champion in the game to (for some reason) get naturally bonus scaling to his basic attacks to an amount potentially double that of other champions. And yes I know he won't ALWAYS hit you with every pellet, but it's usually 2-3 which still deals more damage than it should.

And I'm not even saying it's hard to win a game against Graves, because he doesn't offer much utility to his team and with enough CC he can die in a fight. I just feel like his scaling basic attacks are about the weirdest things to have in the game, especially since it isn't OBVIOUS that his basic attacks scale with level, and it seems like hidden power. I don't mind his 150% bonus AD scaling ult, or the 195% bonus AD scaling Q (at max rank), or his smokescreen. The only things that really bothers me on Graves is that he has 2 pieces of hidden power to him that can't exactly be accounted for. His basic attacks, since you can't even guess how much damage his basic attack will deal by looking at his AD, and his E, since unless you take the time to click on him and look at his buff bar for how many stacks he has, it'll be hard to determine just how much tankier he can get.

TL;DR - Main thing I'm asking is if Riot could get rid of the stacking on his E and make it a flat amount, or get rid of his ability to keep it as long as he's in combat and make it a fixed duration, and make his basic attacks a consistent amount of damage throughout all stages of the game. He can be compensated in other areas feel free, I just personally really don't like those parts since it's a very big piece of hidden power.

Edit: I'm not saying that Graves is OP or Broken. I think he is really balanced right now. But aside from the balance I think he just has some hidden power that could be put somewhere else behind his Basic attacks since the AD Ratio they go by increases with level, which is weird.

/end rant.