Arshei,
Please excuse me if I've got it wrong, but it seems as if you enjoy hating Cullen. You love to hate the character. More power to you, in my opinion. As a murderous, mad, mage-hammer, Cullen is a compelling character and can really get the emotional juices flowing.
In truth, I get the same thing from him, only I ignore whatever rumored, retcon correction has been made to canon by developers. I ignore it because I liked their first idea better. You can ignore it if you choose too and play your games accordingly. And you and I are not alone. Some of the fanfiction surrounding Cullen the mage-hammer I've read has been really, really good. Sometimes he's redeemed, sometimes he's a tragically irredeemable character. In my own version of Cullen-centric fanfiction, he dances around a role similar to Maferath with his lover, Magequisitor. That remains unfinished for reasons I won't go into here.
The people who love to love Cullen are entitled to their enjoyment too, though. Insisting that it must be your way, that Cullen is a murderous tyrant who deserves to die, doesn't really gain you anything. You can love to hate him without the agreement of others. And now that you know how to get the dying beggar Cullen in your games, go for it! Knock yourself out!
Whether Cullen inspires to thoughts of perfect fantasy romance or thoughts of vengeance, he is an inspiring character worthy of a place in three games now. That's something.
Enjoy!
P.S. I always like to head-canon Cullen redeemed by a strong mage who is just as good as Pride Demon Uldred is bad. It's a shame to me that DA:I glossed over Cullen's peacemaking with his torturous past. It must've been a time and money issue. Someday when I get the brass, I'm going to take the whole Maferath/Cullen role to the end. And I understand perfectly why you might like to see the Trespasser slide of Cullen wasting away in a ditch. You enjoyment of that slide neither breaks my bones, nor picks my pockets. 