Wasn't there someone claiming that they had to slaughter all the hiding tiefling kids in order to push forward the plot...?
Either way, I don't get why you are so wound up about this. The 'preset' option seems to be going the good aligned playthrough, that's usually what most people do. Goblins have been very humanized in this game, and I have to admit, as much as I disliked them being made so smart and civilized, I found some of them very cute, I grew fond of Zassa or Sazza and I couldn't be mean to her in my evil playthrough, I had to spare her. Still, I'm sorry, but they're effing gobbos and 99% of them are evil (I haven't found a single good gobbo in the game, so I leave that 1% open.)
The children that you can kill, but you don't have to kill (I didn't even manage to catch them in my playthrough, they darted off so fast!) are clearly growing up to be just as evil and already behaving like psychopaths, they are shown torturing other creatures and enjoying it thoroughly. There is clearly a difference between them, and the tieflings, as much as you wouldn't like to admit it, the goblins are still a monstruous race, and their culture revolves around cruelty and back stabbing.
My criticism is to have the option at all, since it is one of the few things in the world across time people can agree on as being amoral. In any world it would have social, professional and therefore personal consequences, which are not represented in this game, hence having these interactions themselves is worthless other than filling the desire to act as an inhuman being. Even people inclined to that sort of behaviour know it is wrong and refrain from doing it, because of the attached consequences, hence it is a statistical outlier and always has been. Even if you go by the definition of them being just vermin or animals, taking a puppy behind the barn is not something anyone would do for fun and is quite stressing for the individual.
If one agrees that goblins are humanoids with a culture, that might be alien to us, we are now in a society (and this western society is represented in this game) that respects that and does not directly make the assumption that different cultures are inherently evil. Besides, cruelty to animals is a totally human behaviour, especially as a child, I bet everyone of us has a story of witnessing or acting on causing an animal mental or physical stress and pain deliberately inflicted for a varied amount of reasons.
In the end it barely matters for most the players, but if your game wants to represent the society of liberal standards of today, this is something to keep in mind for the devs.