The empire did nothing wrong
The greatest form of government is benevolent dictatorship.
The Empire is the closest thing to that, since you have a strong central government headed by a level of wisdom that could only be achieved through the force.
The rebels want to destroy that central guidance which connects the entire galaxy, and replace it with the same system that lead to corruption, war and power abuse that necessitated the Empire to begin with.
Sure, Palpatine orchestrated the Clone Wars, but it was going to happen one way or another. At least under his oversight, all of the separatists could be identified and destroyed, and the Republic would actually ve prepared to fight them.
If it weren't for Palpatine, the separatists would have easily broken the republic and lead to corporate warlordism.
To take what Thrawn pretty much outright says, because you see the events through the Rebels point of view, on their heads they just believe the Empire is continually plotting to do harm to every innocent little guy in the galaxy.
As we clearly can see, that view of the Empire is far too dramatic.
The Empire is a effective form of government in that it kept billions of beings perfectly fed and clothed.
Day after day, year after year, on thousands of worlds, people live their lives under Imperial rule without seeing a stormtrooper or hearing a TIE fighter scream overhead.
