I understand you based your opinion on your personal taste referencing to the dramas that you loved. First of all, this thread is created for Haechi fans. If you feel like this drama didn't pass your personal standard, don't watch it. You don't need to leave hate review here. Besides, how can you have the right to share your review if you only have seen the surface of the drama? And you don't need to make emphasis that you don't like the female lead either, that is irrelevant since you already mentioned "it has several of your favorite actors" ...
And yes, Haechi has a modern touch. I, too, is a big fan of Jewel in the Palace, I also have watched Dong Yi, and even the legend Jumong. I have never seen Yi San, but the writer is the same as the writer of Dong Yi and Haechi... And I can say, Haechi and Dong Yi have so much differences when it comes to screenplay and direction. Haechi has a modern touch, and unlike Dong Yi, it is not a fairytale-like love story type. It focuses mainly on the political issues.
The plot actually is written almost accurately based on the Korean history. If that is zero sense, I don't know what makes sense in creating a historical drama for you.