Okay we have to keep in mind. Sunwoo is right, this rarely stays limited to fiction. With that in mind we have to understand this is fiction based on a time period and place that is reality. In this case Nohr is based off of the Medieval Europe.
What we do know of this time is that if you insulted your nobility or royalty, you generally did have a date with the ax man, or if in France, the guillotine. In our modern period of time where we actually have a more sensible understanding and do not believe royalty are chosen by gods (or as some cultures claimed, are in fact gods). However in that time it was not the case, they were the closest anyone got to God and insulting them was borderline blasphemy and treason against the crown and dealt with as such.
So I do see why they chose to mimic that state in this fictional recreation and I can understand why Sunwoo gets heated and does not like it. As for the comment of apathy I have not played the part and can not comment if it would bother me or not, all I know is after the first time walking the Law Path in Tactics Ogre I really had to insist on Chaos every other turn. I figure it was said best in a totally unrelated game, "Do not hate humans. If you cannot life with them, then at least do them no harm. For theirs is already a hard lot." it is an interesting quote and one I feel that anyone with power and is in a better position than another should give thought. You do not need to help them if you do not want to. However consider that their life may very well be much harder than it appears and do even a little part by not adding to their potential hardships.
From what Arvilino said I can actually understand what may be going through Corrin's mind and why they act the way they do. I have to agree the whole scenario of Nohr does not come off as shoddy writing as much as it comes off as having a bad plot device. It may also only be me but I have found most Fire Emblem games have always had a problem with plot devices.