I agree, the changes they made in the drama which we have seen so far does lay a better foundation for the story and gives us more sympathy for Sungcheon. It is really hard to watch a drama where you hate the main character, and the fact that they did not make Sungcheon and Taeyong friends from the start does help humanazing the MC and not make him into the person who stole his childhoods friends life. (Also the changes they made for Taeyongs character is so much more believable. In the webtoon he was naive and just good all the time. But the fact that we see him flawed in the drama is refreshing and helps relieving the hate for the main character as well - as we see that even the "good" charcters make mistakes. Bcz in the webtoon he was basically perfect, from what I remember anyway.) 

But so far I really like the changes because there were several things in the original webtoon which I felt did not make sense, especially the ending. Anyone else who thought that making Sungcheon and Yeojin end up together was just toxic as fuck? Like they were suddenly portrayed to be this happy couple with this family, like they forgot about every toxic moment ever and the fact that they hated each other?