Most of the “random one-shots” (which are quite rare btw) are actually from extreme range, not close range. I’d say give him more damage within 25-30 meters, and the damage falls off to a minimum of 100. This would force a more aggressive and risky playstyle, and maintain his long range one-shot matchup against Widow only.
Reverse damage fall-off would just create a more passive Hanzo, and would actually feel pretty bad as his consistency drops off a cliff with longer distance.
Choke spam (which is not random) is just the nature of projectile, and is completely unsolvable. Damage fall-off would reduce its effectiveness a bit though.
That’s an opinion — same as others have the opinion that oneshots should stay. But you’re entitled to it. Just remember that many won’t agree with you.
See above, however. This would lock Hanzo into the close-mid range (not long range), which would satisfy Hanzo players and reduce frustration from those on the receiving end. I’m surprised the devs never even thought of this.
As far as Widow goes, she could take a small nerf to her range, but she’d need some compensation in return, be it in form of a stronger Venom Mine or shorter cooldown on Grapple. However, you absolutely can’t remove her one-shot entirely. All you can do is try to reduce frustration.