Great discussion. Anything that brings more pre-modern history into Dragon Age discussion is quite right by me.
Some points:
Most of what we learn about the history of Thedas will be inaccurate and biased, and as the Couslands have been an influential and respected family for so long recently, much of the context of those past events will be lost. While people in 9:30 Dragon overlook their resistance to Calenhad's unification , I'm sure that at the time they were looked on with much suspicion and derision for their deviant behaviour.
Which leaves us with the situation in 9:30 Dragon. You're right, of course: Bryce Cousland and his pack are beloved. Their device is even a Laurel Wreath. Very peaceful. However, that trusting and welcoming attitude - part of what makes them so popular - leads to their brutal destruction. It's entirely because they have done nothing to deserve it that I find the fall-from-grace story to be so compelling. It shows that bad things just happen, even if you've done everything possible not to 'deserve' it.