The entire franchise is presented exclusively from the point of view of the Republic and the Rebels.
Alderaan and its government was using its label as "pacifist" to drum up money and support for a rebellion against a legitimate government. There are no Wookie genocides in the canon, and the only Wookie "genocides" mentioned in the old non-canonical EU books are, wait for it, only reported after the fact by someone who has every reason not to be any sort of objective or reliable about it.
If we're bringing the EU into this...In truth, the Jedi earned what happened to them. They enslaved and persecuted the sith species for thousands of years, attempted genocide on multiple occasions, and finally succeeded in annihilating the entire race of Force-sensitives. This was after they'd created the sith-human hybrids who would found the Sith Order. Their chronic, pathological inability to handle their own shit bit the Jedi in the ass again and again. They created the fallen Jedi who discovered the sith and created the Sith. They failed to treat or redeem those Jedi, choosing instead to shrug and send them off into the galaxy to do whatever they wanted. So began the almost never-ending wars between the Jedi Republic and the Sith Empire. Seven thousand years of warfare, despite the fact that the Sith should never have been a serious threat to the Jedi or the Republic. The Sith Empire never controlled more than a fraction of the Republic's worlds. And its smallness and human/sith-centric culture meant the Sith cult never could have numbered more than a tiny, tiny percent of the Jedi available at any given time. The Jedi outnumbered the Sith thousands or millions to one, depending on the time period. And they couldn't handle it.
In the canonical franchise, the Jedi are a factory that manufactures psychopaths: emotionless superhumans trained to fight and kill with only the barest nod towards nonviolent problem-solving. They are called out on this over and over in Clone Wars, and none of them have a good answer for it. They all but seized control over the Republic from the Senate: exercising undue influence or outright taking control of diplomatic relations, military affairs, economic policy, and on and on and on. Whether they were actually any good at any of that or not.
The Jedi weren't just corrupt and stagnant. They were actively the cause of all of the Republic's most serious problems. They were incapable of, over and over again, actually dealing with those problems. Those two things, those two facts, cost billions or trillions of lives. The Galactic Empire was small beans compared to the tyranny of incompetent self-congratulations of the Jedi Republic.