Just to be clear - you can't really "reverse" most things. The arrow of time only moves in one direction. People who are jailed and then exonerated do not have their lives "reversed". Their future circumstances are changed. Maybe they are compensated. But they still suffered in jail. You cannot erase that part of their reality anymore than you can raise the dead. This is not to discount your point that making amends while someone is still alive is seen as preferable.
Of course, attempts are made to "reverse" even after someone had been put to death. Posthumous pardons are a thing. It may not bring anything to the person who has passed, but it could give somewhat similar benefits to living descendants.
It's just to say we shouldn't undermine how impactful something like incarceration is on the theory that it is "reversible". Evidence suggests such experiences mess people up in pretty severe ways. Lets also remember thinking of death in these distinct terms may be very cultural. Few penal systems escape barbarity. There are worse things than death. There are many instances or societies were it is preferable or expected people kill themselves rather than go through something like the ignominy of incarceration.
As to the last line, I'm also not sure. Brutal societies have a way of turning on themselves. Nations that accord more protections to their people are generally a better place for their rulers, even if the reverse is not always true. Personally I would love a legal system that baked into its norms higher punishments for people with more power. I think these have existed in the past, even if enforced through less modern mechanisms.
It is also the case that people in power do things that people with less power are incapable of. Getting rid of notions of executive privilege or qualified immunity would be a good start. The way the law is written currently, people in power won't simply not be punished - they won't even be charged. Take George Bush. Did he ever even just have to testify under oath about the rationale for the Iraq War once? Would the United States really descend into a banana republic if he had been charged for perjury or war crimes? It seems like the push in that direction can instead trace its genesis to the fact that in America, we evidently make our leaders untouchable.