So like...what was the point in the reincarnated plot?

I think is an easy way to make children have an adult mind and behave like one :/
Even tho they act childish
I'm not complaining, I like it hehe :p

I agree but more than that, from what I take from the emotionla sid eof the story is that them being reincarnated with theirbold life's memory intact is to deepen their emotions. Because if they are just children they can easily forget like in some way makes them to open up to their father faster. But since they are aware of the situation they know the history and how things started it adds up to their distrust and see the Royal family as hypocrites and the addition that most of the nobles look down on them, having Duke Rosea show up with his "kind" approach made the twins trust him more. (⌒▽⌒) well that's just my opinion, but we can view their actions differently base on how you sync your emotions to the story.