Because the hit box issue didn't just hit Hanzo, it actually messed up all non-hitscan heroes, as all of them got nerfed by the smaller model hitboxes. Even so, based on the PTR, his arrows still are not big enough to hit people around walls unless part of the model is visible, so they did add something else to try and stop the around the wall hits.I really don't understand why they are reversing their position on Hanzo. They admitted he was too powerful, they commented on the video everybody saw where he got a head shot around the corner, but now, nevermind, fuck all that shit! Hanzo Hanzo Uber Alles!
They never felt he was too powerful though, the behind the wall hits were considered a bug, but to Blizzard, his participation in most higher tiers is negligible. He is right now in a similar spot as Mei, there are just way better heroes to take at the higher level, like Widowmaker.