But that is just it, isn't it?
Malcolm is an exemplary mage despite not being in a Circle and yet, even him was lead
to use blood magic for the sake of his family. If he can fall, anyone can.
And while you are right most parents will do bad things to protect their children, most parents don't have access to a mage's destructive powers.
And yet, the events of Asunder and the other suplementary material show that Anders was 100% right.
The Templars attacked a peaceful conclave Justinia had called to find a way to prevent the war. They murdered an unarmed, surrendering mage in cold blood, thus causing the mages to fight back, sparking the Circles to break away completely and starting the war in the first place. Before that incident, most of the Fraternities wanted to stay with the Circle, even after Meredith's actions. Fiona's Libertarian fraternity did not have the votes to separate. Afterwards, ALL of the fraternities but the Loyalists decided enough was enough, and voted to dissolve the Circle and break away from the Chantry. The Templars were directly responsible for the war and the Circles breaking away.
The Templars later annulled the Circle in Rivain. Killed every mage there, for the 'crime' of the mages actually being able to visit with their families. They launched an unprovoked attack on Andoral's Reach, a fortress home to mostly refugees trying to stay out of the fighting.
You still want to pretend that the Templars were not out of control, that they didn't abuse their power?
The system was broken, the Circles were an atrocity, and Ander's actions proved it.
The Templars were fanatics. The were specifically chosen for how fanatical they were. Nothing else mattered. Not their fighting ability, not how moral they were, not even how much they actually understood the religion, none of that mattered. How fanatical and extreme they were was ALL the Chantry cared about.
The Chantry had the same criteria for selecting Templars as al Queda does for it's people. The Templars were so extreme, so fanatical, they wanted to overthrow the Divine and take control of the Chantry themselves, and were perfectly willing to kill innocent people, mage and non-mage, to do it.
These are the... things you are defending.