The commentators who thinks what's right is complaining too much about a fantasy novel? Why are you searching for a perfect world in a fantasy story that have their own laws and traditions? The emperor was taught at the very young age that his brothers are his enemy that he needs to be eliminated to become the king. How could he try to change it when all of his life, it's been like that? Made you wonder what happened to have that kind of family tradition when the first emperor seems to be nice (according to the black dragon story) but here goes his predecessors. This kind of time is very strict with their beliefs and traditions and as a reader, you need to apply that to the world you're creating while reading this story or any story because that's how the author wants it to be. Not a perfect parents, not a perfect world.
And please, marrying the empress is the start of the changes and having the princess is the current progress. The emperor and the empress is the start of the changes in their beliefs and traditions.
Girls, girls calm down. He may not have the attitude and the smile of Tang Bo but he looks like the younger version, im talking about the second son if Tang clan. Haha