You could probably say that about Loghain.
And Alistair as extremist? Alistair? Leliana? LMAO you've got to be kidding or WUMming.
Maybe if you were more specific about what you meant by extreme, I could have worked with your definition over just using my own.
Alistar's extremism is more moral absolutism then anything else. He absolutely believes in a universal good and evil and is willing to make extreme choices based on that. It's not really prominent if you play a stereotypical good character, but start treading that grey line or darker and he'll have some very choice words for you, especially during redcliffe and the landsmeet. Understandable? Yes. Extreme? still yes.
Leiliana is a extremists in the same vein as alistar, only her moral absolutism is tied into what she believes is the message meant to be taken from the andrastian teachings. Again, lots of choice words if you play a grey or darker character but not to the point of alistar....until you start to do things that go against the maker's teachings.
Sten would rather die then live outside of what the qun asks for, and he's more then willing to fight the warden if it means doing things the way he feels they should be done. You can earn his respect at least, but he'll let you know exactly how little he thinks of you until you actually do. From thinking peasents shouldn't fight to believing that warriors not strong enough to defend their own land should be killed, he's a very devout follower, as is required to make the rank of sten.
Morrigan is stupid evil, no way around it. She likes it when you do evil things and say bad things to people. Hurting people is her major turn and helping people for your own goals is akin to being barney the dinosaur as far as she's concerned. And let's not kid ourselves in thinking she has anyone elses interests at mind then her own, she's as manipulative and calculating as her mother, if still inexperienced enough as to not be completely ruthless and detached from those she's using.
None of these characters I would describe as bad in terms of quality. I wouldn't change them or demand they be changed because I don't agree with their stance. It's actually a good thing, in my opinion, to have characters who you don't agree with on your team to give you another perspective to consider. But at the same time, I feel that while origins had characters like wynne, oghren, and zevren to an extent to act as the grounding dragon age 2 didn't. Then again there were a lot of things dragon age 2 didn't have, but that's besides the point.
Having a character be a badass neutral is just something I think hasn't been as touched upon as it could be. Between origins, awakening, and 2 I don't think there have been as many as there could be or should be to balance things out in a way that doesn't have them never address their comrades positions or voice an opinion on it, when so many other times, the extremes criticize them in every ambient dialogue opportunity they get.