Well, you asked measured feedback:
Okay, let’s do it. This will be specifically in reference to Cassidy and Hanzo.
First, let’s get the obvious out of the way:
Power
Both heroes were before the patch dominant heroes. They are over represented in play and over performing when compared to other heroes. These buffs are pure power increases on heroes that do not need them. There are no downsides. That alone makes them bad changes.
Okay, that out of the way.
Cassidy:
The problem when dealing with Cassidy is a combination of output and lack of weaknesses. His output is higher than most heroes. The fire rate and damage value for his shots means he represents a threat at a decent range. Most heroes cannot put out damage sufficient to reasonably compete in a range shootout. To attack him requires being behind a shield or taking cover otherwise the damage he does, even with less accuracy is just to high for most heroes to be able to kill him in the same window he can kill them. At the same time between flash, fan and roll getting in close is also a significant disadvantage. At the end of the day, he really has few weaknesses you can exploit, especially compared to other heroes.
This is where the first real problem comes in. The air roll effectively removes an option. He can’t really be displaced by any mechanism anymore. This reduces possible ways of dealing with him. And, as he already has few it is very felt.
Additionally, the faster movement from jumping and the ability to cross gaps both makes it easier for him to escape when he is in trouble as well as engage on your. This feels very similar to the issues caused by his longer roll distance, which had to be nerfed. He can now engage on your from further to do his flash>fan. This can easily put a lot of heroes in the realm of ‘nothing I can do.’ Which is obviously a bad place to be.
In short, the buff allows easier offense and quicker escapes. Both of which make dealing with an already hard to deal with hero even more imbalanced.
Hanzo:
Hanzo is similar to Cassidy in the fact that he gets a lot of value at range. The difference is often it feels very random. Spamming arrows towards a team is a very rewarding tactic. Even body shots take a significant amount of health. And get a head shot and you often get a kill and a fight win. Coupled with the raw burst (especially on tanks) of Storm Arrows, it often is at best problematic to deal with. And there is a lower skill requirement because so much value ends up being just from those random head shots. And like Cassidy he is also hard to deal with close range. Storm Arrows gives him an almost shotgun response when dove.
And this is where the change gets really problematic. On some characters you can outplay his rapid fire and dodge around. The problem is now the bounces mean you not only have to dodge the first shot, you have to dodge the ricochet. Wall behind you can mean that it bounces back into you. He can miss and hit the ground or a stair and have it bounce into you. This drastically reduces his skill requirement in fighting off a dive. It drastically lowers the options for dealing with him.
Additionally, there is already the issue of spam 1-shots. Having those coming around corners where you cannot see them until you just die is a really bad design. There is really little counter play to him spamming potential 1 shots around a corner.
In short, the change adds to the random value, negates options to deal with him and just makes the already strong hero more obnoxious to deal with.