Why are the songs in Zhen Huan's biography so ugly?

In fact, the episode of Zhen Huan biography is still very bold. Recently, the episodes of TV dramas are all folk singing, which are generally based on love songs of idol dramas or sad tunes when they are sad, and most of them are catchy. Empresses in the Palace is well-made, and the episode "Feng Huang Yu Fei" is sung by the famous singer Liu Huan himself, which is magnificent. Almost every song in the play is Bel Canto, which fits well with the scenes and characters in the play. What a joke do you think it would be if Zhen Xuan played a rap while playing the guqin, so it's normal that you don't like Bel Canto, but these songs really fit the show.