Lin was only okay with you being her master because you've been the best master she's ever had. MC treats Lin very equal and helps her with almost anything she needs.
Once Lin fell in love with MC, she said she would like to have a child with him, but she would never want to bring a half elf into this world because they have no rights. This happened quite a while ago, it was in the background because the focus was on her character (learning about her, fixing her, unlocking sex, etc). The slavery aspect of the world is in the foreground now because this is one of the last problems she has to deal with, but it's also one of the hardest. The rest I mentioned above has largely been solved and there's no point in going over the same story points over and over again.
Lin has never accused anyone of being an "elfphobe", I don't know where you're getting this.
Harem Hotel has never been only a dating sim. As it says in the description of this game: "Upgrade your hotel, build friendships with them, follow their stories, and train them."
While it certainly has dating sim themes, and will continue to have them, my goal for this game is more than just meeting a girl, fucking her, marrying her, and seeing the end screen.
Harem Hotel is a lot of things. Thematically it's a fantasy contemporary sci fi. Some events like Ashley's are emotional, some like Nia's are action packed. In the end, what this is, is my story.