Ok, a lot of comments so I'll elaborate a bit more:

1) Q max LUL: Yes, I am aware that it's common to max E second, as most top lane match ups are melee vs melee. And yeah, E is arguibly Jax most powerful basic ability. But in hard range match ups you have the choice of skilling 2-3 points in Q to have a bit more agency in your trades, since it widens the window between your Gap closer CD and their disengage ability CD (Jayce knockback, vlad pool, gnar hop etc). And that's the point, you give up some raw damage to earn a higher ability to engage and deal damage. With this buff that choice is removed.

2) Why does it matter? Jax has three main ways to execute positive trades in lane. Lvl 1 cheese with E; Pre 6 all ins with Q and high passive stacks; Post 6 all ins with Q, high passive stacks and an ult proc ready to go. Most of these are gated through Q CD, not only against ranged opponents, but all of them. Not to mention that Q is also his main disengage through ward/minion hopping. Q reduction implies increased target access of a character that is incredibly powerful at melee range, with no trade off whatsoever.

And Jax isn't even in that bad of a spot at the moment, most of top lane matchups are even, except for GP and maybe Renekton, but eventually you will outduel them regardless.

If what you want for Jax is a better match up vs ranged laners, maybe reduce Q CD at ranks 2 or 3, so he gets more trade oportunities but giving something in return, not an overall raw performance increase.

TL;DR: Jax is pretty good, if u need better lane vs ranged decrease Q CD at rank 2 or 3 to have a tradeoff not an overall buff