Before we continue, can we acknowledge that it's very easy for the Rebel Alliance to look like villains without context? When the first major battle occurs in Rebels, the only thing we've seen the Empire do is arrest someone selling food without a license. Sure, they're a little dickish about it, but come on. Food safety is important. The Rebel forces, on the other hand, set off bombs in a populated city, steal Imperial cargo, and gleefully shoot down soldiers in the street. These aren't the underdog Rebels who fled a Star Destroyer; these guys start on the offensive, and prove to be a significant threat. It's no wonder Darth Vader is hunting them personally by the time Episode IV rolls around.
But don't worry, these Rebels are cartoonishly good-hearted freedom fighters, not terrorists. The Ghost's mercenary crew is motivated by pure intentions, and will do absolutely anything to help the common alien. Those cargo crates were filled with food the Empire kept from starving farmers who were evicted from prime real estate. Meanwhile, Stormtroopers openly use Wookies as slave labor, and anyone questioning Imperial policy is arrested for treason.
Sure, I get wanting the Empire to look bad, but that's pretty heavy-handed, even by cartoon standards. At one point a Stormtrooper stops fighting rebels so he can literally chase a terrified Wookie toddler for five minutes. The murders of Uncle Ben and Aunt Beru were more subtle than this, and it reduces everyone involved into one-dimensional archetypes. Thankfully, once we've established that yes, the Rebels are good and the Empire is unredeemably evil, we can start getting to the fun stuff.