That's one of the thing i detest about Alistair which is his ineptitude in judging a situation for what it is rather than always joke like an idiot especially his ineptitude in terms of personality that make him the puppet of the PC who is able to command him to beget a child.
I took Morrigan with extreme rigor and severity and kicked her out with a fierce glance and that was priceless seeing a PC who do not falter unlike this idiot.
It fits his personality though. Alistair is a weak man who uses humor to cover his insecurities. So do you detest the character as in he is somebody you wouldn't like, or do you detest the character design?
The situation bothers me on the design level. It's compelling a party member to do something they express discomfort about. How far should video game protagonists be able to go to convince, persuade, or force another character to do something?This case is far more critical than the Loghain decision for Alistair which is about beget a bastard and Alistair lived this as a trauma for his entire life with someone he hate.
In Dragon Age, the player character-companion relationship basically boils down to "hey player, make my most important life choices for me" from the companion's point of view. Some of these are framed better than others but you can feel pretty uncomfortable over having to decide a personal matter for someone.
In DA:O, many companions had hard limits on how far you could push them. some companions will leave the party if you're enough of a jerk to them, but that feels more a like a judgment about your overall leadership style than violating a specific core belief.
I can also see beliefs about when life begins and when human beings gain a spirit/soul playing into this too. Some players and characters might not be OK with procreation as a utilitarian act instead of its own end.
But isn't it good design that you have to actually argue with him and convince him via proper responses? Ultimately this format is limited because there are "right" answers that you can know or look up, but it still exists. He's at least a person and not just an instrument of the PC's will. That he gives in is part of his character, who is quite weak willed.
And as to the last bit, players have the option to role play that.
Because if Kieran has the Old God soul, this would be within Morrigan's original plans which didn't include sentimental notions and love.
The addition of the Warden and later the development of maternal feelings would be just an unexpected addition to the original plan.
If Kieran is a normal baby produced unexpectedly due to natural reasons, having a son and being in love with the Warden is a bigger deal in the context of Morrigan's character development.
In this case the experience of living with the Warden and their normal human son is a completely unexpected turn of events for Morrigan which are influenced purely out love and generally notions she used to mock.
The addition of feelings still changes things. I had my Warrior go through the mirror with her in Witch Hunt. You're on to something but I think you have it backwards. Yes, Morrigan might have a complete character shift if she has a normal child and now her plan is toast, but I find it far more intriguing to see what sort of monkey wrench those feelings are in her original plan!