It's fiction. I know that.
What I'm saying is Sebastian puts a "face" on the victims of the Chantry. That the people Alistair killed aren't a bunch of statistics but family, friends, and loved ones of people in Kirkwall.
In Sebastian's case, a kid-brother figure.
I'm sorry, it's just tiresome that so many people seem to imply that players are horrible immoral monsters just because they had a character keep Anders alive.
Still, that's not my reason for taking him out of the game. It is, as I said, the way he is implemented is heavy handed and disruptive to the existing scenes. When I first played the end I had him there and I could barely make sense of what exactly was happening. Who said what to whom, what the arguments were. The conversation doesn't flow as naturally as it does without him there because he's constantly interrupting everyone.
Besides, I didn't find him very interesting. Sure, he's undeniably pretty to look at, and he has a lovely voice to listen to, but he didn't really have much to say as a character. So, I keep him out of the actual game, as he doesn't provide much added value for me there. I add him back in in the Keep when I recreate the save game.
Also, I think he's very hypocritical. Waging war on a city, slaughtering dozens, hundreds of soldiers and civilians just to get at one person? What a way to honor Elthina's memory.