Graves changes in 5.8?

So, I'm a little confused about the (as yet unofficial) change to Graves's Q. (Link above, scroll down one or two Teemos.)

I thought Graves was in a pretty good spot. He's strong early game and falls off late. He's good at burst but somewhat lacking in sustained damage (partly because of his range). He's powerful but not oppressive. Strong champion, but clear trade-offs and weaknesses.

So, now we're nerfing his burst? Why?

This isn't a "QQ my main adc can't steamroll unconditionally anymore" thing. I actually almost always prefer to play Quinn, who can't be reasonably accused of being OP. My friends do usually insist I play Graves, because he's the only adc who's tanky enough for the kind of stupid shenanigans I pull, but I wouldn't say I main him, and I don't want him to be OP. I just didn't think he was.

Also, the compensation he gets for hitting one target with more than one bullet—does that even mean anything? I don't think I've ever been able to pull that off. If it's possible, it requires invading their personal space more than I've been comfortable doing.