I feel like they're really trying to appeal to all of their audience just in different ways. For newer fans/people who liked Awakening both old and new, marriage and kids are coming back with the addition of the face rubbing and Phoenix Mode. For the older fans/people who didn't like certain things in Awakening both old and new, we have a game that's supposedly harder, a revamp of the weapons triangle and new classes. If the kids aren't integral to the story, you can probably just not recruit them so it's not a big deal, but putting them in gives people the option just like Phoenix Mode does; people don't have to use it, it's there for others who might want to.
The issue is ofc how that kinda stuff affects the overall game - does Phoenix Mode/the face rubbing/kids returning have a big effect on the story at all and if it doesn't, then is it really justified to include it? Or should you spend that time on other things in the game? For IS, they probably feel like it's safer to just include it and then whoever doesn't like it can just ignore it. And I mean, looking at how people tend to operate, the people most likely to complain about things being included will still buy the game because they can ignore this stuff but the ones who might be mad that it's not there are probably more likely to skip it. In my experience anyway, it's easier to ignore stuff (especially if it turns out to be non-integral storywise) than it is to ignore that stuff you want is missing.