I'm sure the thread is going or has already gone off topic.
Anyway, I can't speak for anyone else here but these are my reasons for wanting Cullen as a companion/LI
I did think that his crush on the female mage warden was cute and he seemed to be a very sweet guy. Then he saw all his friends and comrades get killed and possessed in horrible ways. Out of all the Templars trapped inside he displayed remarkable strength and fortitude. When he was set free his reaction to want all the mages dead was understandable and I don't blame him for it one bit.
In DA2, I was happy to see Cullen, handsome as h*ll and doing what a Templar is supposed to do, his job. When you talk to him he seems to be more level headed and reasonable than my last encounter with him in DAO. He sees mages as dangerous but still remarks fondly about his crush. He's tough yet still display that same shyness we've seen at the start of DAO.
I don't care about his views on mages cause it's not like he is totally wrong, except for when he says they aren't human. He doesn't coddle mages nor is he a tyrant. sure he was removed from the Fereldan circle because Gregoir thought he would fit in at Kirkwall, but that is just Gregoir's opinion that was proven false. Cullen seemed to be having a bad time of it at Kirkwall as he wonders if they are doing their jobs right or just doing whatever Meredith says. Cullen most certainly is not an extremist, he just does not believe in being too leniant on mages.
I would say that he would make an excellent Knight-Commander.
I would love to have Cullen as a companion cause I want to travel around with him, get his insight on what is going on, and totally stomp any mages who get out of line with me. I don't want to hear any whining about how I should hug everyone, I want no more crybabies blubbering in my ear about their different sides of the story. I liked Fenris and agreed with many of his points but I was sick of his whining just as much as I was sick of Anders. I want someone with a level head on my team. I admire his strength, level headness, and remarkable willpower.
As for Cullen as a LI. The man is straight up sexy and I don't mind a shy guy.