The rapists only threatened a few people in the city, whereas Imshael now threatens an entire country and thousands of lives.
A spirit of choice who was released by a chevalier, and who was initially summoned by atypical Dalish elves who violated the tenant of the Dalish.
Also, I'm not condemning all elves. I'm condemning the Dalish clans. So it would be more like condemning the Templar order for not controlling their members (which I do).
Because an elven mage violated the ethos of the Dalish and summoned a spirit? If the Dalish traditionally avoid using magic that involves spirits, I don't see how you can condemn them all for it.
The best equivalent I can think of would be groups of gypsies wandering around europe being a nuisance and illegal squatting on land, completely out of reach of the law, and some of whom have been found to be creating atomic weapons. Like hell should they be allowed to keep doing that.
The majority of Dalish mages avoid using magic that involves spirits, unlike the Circle mages. "Unlike other spellcasters, Dalish mages do not use any magic involving spirits, as they believe all spirits are dangerous." (page 104 of WoT)