First, anyone who actually thinks Akechi is dead, *ryomalaugh*.jpg. Yeah he ain't dead. Just wait for P5A or whatever other sequel/spinoff they do.
Second, I honestly think Akechi himself is fine, it's just his last few moments that are a wreck. I can get what they were going for, but I felt it all happened way too fast. All you really get of him after the massive ass plot twist is a small inner monologue and one or two conversations with Shido, which really isn't enough. I probably would've had the team confront him at the beginning of the palace and then have him join again (I wanna use Loki) to help take down Shido all while they constantly remind him that he's a piece of shit and maybe even have it to where he's agreed to turn himself in after taking Shido down. They could also have him interact with Sae a bit before you're given full access to the palace. The boss rush in the engine room could have you fighting cognitive Akechi instead of actual Akechi and the end result still has him "dying" to save the team.
Also, it only recently hit me that for all the people hating Akechi because he's fake as a $3 bill, that that's pretty much the entire point of his character. Hell, he even flat out says it during the fight with him.