In this version .... There's no reason for Hae Soo not to love Jung .... he's all u said and more, in fact his fun straight forward personality suited her the best!!

In original SH, personalities were different... 14th was even better and cleverer than Jung .... but also, she was way more clever than Hae Soo - RuoXi admired 8th's intelligence who was more virtuous than Wook .... and fell for 4th (who was more calculating than Wang So) b/c he seemed to be able to understand her personality and freethinking ....
14th was adorable but too pragmatic for progressive and free-thinking RuoXi  ... he couldn't understand why she made some of the decisions she did .... He repeatedly said "I don't understand women... I don't understand what u r thinking!" ..... So RuoXi understandably, couldn't get over a deep-thinker like 4th.

But easy-going Hae Soo should have loved the adorable Jung, who could have made her very happy!

there is no comparison between So and the other brothers. He is courageous, generous and sensible. He had a very sad childhood and now just wants to be loved with Soo. Also he preferred to be King for not having yet to be blackmailed and risk that the people he loves are killed. Jung was bad to show that they were a happy couple in love and hide the letters Soo sent to the King. I hate Jung!

@Raincat, he didn't really have hide them but repackage them , so the king didn't know it was letter from soo he was thinking it was letter from jung
Soo loved the king so much and wanted to see him a last time befor she die but  she died  without seeing him 

I just wished his love for the 4th prince was more....sincere.It's ok that she loved the 8th prince first but she just couldn't make me believe her feelings...

i think jung was more pathetic than the the other two though. i would never trust a brother who insult me by saying he is ashamed to be born in the same womb as me just because he was sucessful in helping our female lead does not make me much impressed when he created many troubles, example he had equal hand in kiling king wang moo as much as 8th and 3rd, as you mentioned he was a general but he was disloyal to his king and aloving brother even after knowing his family is going to kill moo what a  GREAAAAAT warior and genearal . regarding 4th prince there was no choice for him but to get the throne. he would be pathetic if he would ignore his brothers being killed and people being tortured just for one woman he loves. many lives vs one life you know. and i dont think he was selfish it was necessary or else he would be forced to kill more brothers. well he wanted get married to run away with her but she was the one who rejected him. and wang yo was brother of jung not father. well if you only care about romance in the drama then jung is okay but there is much more to this than romance you cannot call the other princes pathetic just because they were not able to help the girl. sory but jung was a spoiled brat who had no idea what burdens are.4th never harmed him or his family but he was always blindly hating him that itself shows his character. 8 th prince let his thurst for throne deviate from morals and kill people for it but realisation and regrett was his repentance. and  4th did not deviate he became a peoples king yes cruel to people who were wrong but still did the best for general public. but jung neither regreted for his betrayal to moo nor for his hand in separating wang so and hae soo not even a speck of sadness or regret that he was keeping a father and daughter seperate from each other. yes yes he loved hae soo but he lost respect for many more things.