As much as I hate what Anders did, I have to agree with this. Drastic changes aren't possible without drastic measures. And that means that many innocents will get tramped underfoot. Damn. Anders at least was honest enough to recognize that and submit to your judgement (hell, you could make him kill mages for the Templars, in an incredible twist of events).
Incidentally, this is total nonsense. There are loads of drastic changes that have happened peacefully, and without extreme violence.
Take the abolition of slavery, for instance. Only a few countries ended up submitting the issue of slavery to the trial of war, like the United States and Haiti. Britain abolished slavery peacefully. So too did France (more or less...it's complicated). Same with Russia. The Ottoman Empire. Spain. Portugal. Brazil. That's a humongous change - the release of human beings from bondage - and it didn't require a John Brown an Anders to do it in most countries.
Or, for another example, the revolutions in the Eastern Bloc states in the late 1980s and early 1990s. No one needed to slaughter a bunch of Komsomol members or whatever to kickstart a war to bring down communism. By and large, the Revolutions of 1989 and the events surrounding them were relatively bloodless, with most of the few people who were killed being the most egregious criminals under the previous regimes (e.g. the Ceaușescus of Romania).
So radical change can happen without radical amounts of violence. It's people like Anders, who deliberately radicalize a situation by murdering innocents, who do their level best to prevent that from happening.